Add one-skill
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# 聚合模式速查
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## 基本聚合
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### 聚合函数列表
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| 函数 | 说明 | 示例 |
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|------|------|------|
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| COUNT(*) | 计数(含NULL行) | 总行数 |
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| COUNT(col) | 计数(不含NULL) | 有效数据数 |
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| COUNT(DISTINCT col) | 去重计数 | 用户数 |
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| SUM(col) | 求和 | 总销售额 |
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| AVG(col) | 平均值 | 平均薪资 |
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| MIN(col) | 最小值 | 最小年龄 |
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| MAX(col) | 最大值 | 最高分 |
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### 基本用法
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```sql
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-- 单列聚合
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SELECT
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COUNT(*) AS total_rows,
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COUNT(DISTINCT user_id) AS unique_users,
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SUM(amount) AS total_amount,
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AVG(amount) AS avg_amount,
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MIN(amount) AS min_amount,
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MAX(amount) AS max_amount
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FROM orders
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-- 分组聚合
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SELECT
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department,
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COUNT(*) AS employee_count,
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AVG(salary) AS avg_salary,
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MAX(salary) AS max_salary
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FROM employees
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GROUP BY department
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```
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---
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## GROUP BY
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```sql
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-- 单字段分组
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SELECT
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category,
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COUNT(*) AS count
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FROM products
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GROUP BY category
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-- 多字段分组
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SELECT
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category,
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brand,
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COUNT(*) AS count,
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SUM(price) AS total_price
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FROM products
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GROUP BY category, brand
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-- 分组 + 排序
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SELECT
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department,
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COUNT(*) AS count
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FROM employees
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GROUP BY department
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ORDER BY count DESC
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-- 分组 + LIMIT(取Top N组)
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SELECT
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category,
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COUNT(*) AS count
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FROM products
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GROUP BY category
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ORDER BY count DESC
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LIMIT 10
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```
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---
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## HAVING(分组过滤)
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```sql
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-- HAVING vs WHERE
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-- WHERE:过滤原始行(GROUP BY 前)
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-- HAVING:过滤分组结果(GROUP BY 后)
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-- 示例:筛选订单数大于10的用户
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SELECT
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user_id,
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COUNT(*) AS order_count,
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SUM(amount) AS total_amount
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FROM orders
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GROUP BY user_id
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HAVING COUNT(*) > 10
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-- 多条件 HAVING
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SELECT
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department,
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AVG(salary) AS avg_salary
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FROM employees
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GROUP BY department
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HAVING AVG(salary) > 5000
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AND COUNT(*) >= 5
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-- HAVING + ORDER BY
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SELECT
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user_id,
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COUNT(*) AS order_count
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FROM orders
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GROUP BY user_id
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HAVING COUNT(*) >= 5
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ORDER BY order_count DESC
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```
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---
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## 去重计数
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```sql
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-- COUNT(DISTINCT)
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SELECT
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COUNT(DISTINCT user_id) AS unique_users
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FROM orders
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-- 分组去重计数
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SELECT
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date,
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COUNT(DISTINCT user_id) AS unique_users,
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COUNT(*) AS total_orders
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FROM orders
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GROUP BY date
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-- 多字段去重计数
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SELECT
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COUNT(DISTINCT user_id, product_id) AS unique_user_product_pairs
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FROM order_items
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-- 大数据量近似去重(性能优化)
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SELECT
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approx_count_distinct(user_id) AS approx_unique_users
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FROM orders
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```
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---
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## 集合聚合(数组结果)
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```sql
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-- collect_list:收集为数组(不去重)
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SELECT
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user_id,
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collect_list(product_id) AS products
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FROM orders
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GROUP BY user_id
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-- collect_set:收集为数组(去重)
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SELECT
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user_id,
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collect_set(product_id) AS unique_products
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FROM orders
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GROUP BY user_id
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-- 取数组大小
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SELECT
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user_id,
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size(collect_list(product_id)) AS product_count,
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size(collect_set(product_id)) AS unique_product_count
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FROM orders
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GROUP BY user_id
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```
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---
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## 多级聚合(ROLLUP / CUBE / GROUPING SETS)
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### ROLLUP(层级汇总)
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```sql
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-- 从右到左递减分组级别
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SELECT
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COALESCE(year, '总计') AS year,
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COALESCE(month, '全年') AS month,
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COALESCE(region, '全国') AS region,
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SUM(sales) AS total_sales
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FROM sales_data
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GROUP BY ROLLUP (year, month, region)
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-- 结果包含:
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-- 1. year + month + region 分组
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-- 2. year + month 汇总(region为NULL)
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-- 3. year 汇总(month,region为NULL)
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-- 4. 全表汇总(year,month,region为NULL)
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```
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### CUBE(全维度组合)
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```sql
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-- 所有分组组合
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SELECT
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COALESCE(year, '总计') AS year,
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COALESCE(month, '全月') AS month,
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COALESCE(region, '全国') AS region,
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SUM(sales) AS total_sales
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FROM sales_data
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GROUP BY CUBE (year, month, region)
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-- 结果包含所有组合:
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-- year+month+region, year+month, year+region, month+region
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-- year, month, region, 全表汇总
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```
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### GROUPING SETS(自定义组合)
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```sql
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-- 指定分组组合
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SELECT
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year,
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month,
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region,
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SUM(sales) AS total_sales
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FROM sales_data
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GROUP BY GROUPING SETS (
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(year, month),
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(year, region),
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(region),
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()
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)
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-- 等价于多个 GROUP BY 合并
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```
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---
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## GROUPING 函数(判断汇总级别)
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```sql
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-- GROUPING(col):判断该列是否为汇总产生的NULL
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-- 0 = 真实值, 1 = 汇总NULL
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SELECT
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year,
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month,
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SUM(sales) AS total_sales,
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GROUPING(year) AS is_year_total,
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GROUPING(month) AS is_month_total
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FROM sales_data
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GROUP BY ROLLUP (year, month)
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-- 用 GROUPING 区分真实NULL和汇总NULL
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SELECT
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CASE WHEN GROUPING(region) = 1 THEN '全国汇总' ELSE region END AS region,
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SUM(sales) AS total_sales
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FROM sales_data
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GROUP BY ROLLUP (region)
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```
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---
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## 条件聚合(CASE WHEN + 聚合)
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```sql
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-- 分条件统计
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SELECT
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date,
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COUNT(*) AS total_orders,
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SUM(CASE WHEN status = 'completed' THEN 1 ELSE 0 END) AS completed_count,
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SUM(CASE WHEN status = 'cancelled' THEN 1 ELSE 0 END) AS cancelled_count,
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SUM(CASE WHEN status = 'pending' THEN 1 ELSE 0 END) AS pending_count
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FROM orders
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GROUP BY date
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-- 分条件求和
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SELECT
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department,
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SUM(salary) AS total_salary,
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SUM(CASE WHEN gender = 'M' THEN salary ELSE 0 END) AS male_salary,
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SUM(CASE WHEN gender = 'F' THEN salary ELSE 0 END) AS female_salary
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FROM employees
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GROUP BY department
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-- 条件平均值
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SELECT
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category,
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AVG(CASE WHEN price > 100 THEN price ELSE NULL END) AS high_price_avg
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FROM products
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GROUP BY category
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```
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---
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## 聚合 + 窗口函数
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```sql
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-- 分组内占比
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SELECT
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department,
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salary,
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ROUND(salary / SUM(salary) OVER (PARTITION BY department) * 100, 2) AS salary_pct
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FROM employees
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-- 分组累计
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SELECT
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date,
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department,
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amount,
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SUM(amount) OVER (PARTITION BY department ORDER BY date) AS cumulative
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FROM sales
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-- 分组排名
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SELECT
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*,
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RANK() OVER (PARTITION BY department ORDER BY salary DESC) AS salary_rank
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FROM employees
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```
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---
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## 多表聚合
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```sql
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-- JOIN 后聚合
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SELECT
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u.department,
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COUNT(o.id) AS order_count,
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SUM(o.amount) AS total_amount
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FROM users u
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LEFT JOIN orders o ON u.id = o.user_id
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GROUP BY u.department
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-- 子查询聚合
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SELECT
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dept_stats.department,
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dept_stats.avg_salary,
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emp_count.employee_count
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FROM (
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SELECT department, AVG(salary) AS avg_salary
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FROM employees
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GROUP BY department
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) dept_stats
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JOIN (
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SELECT department, COUNT(*) AS employee_count
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FROM employees
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GROUP BY department
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) emp_count ON dept_stats.department = emp_count.department
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```
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---
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## 常见问题
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### 问题1:GROUP BY 字段遗漏
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```sql
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-- 错误:SELECT 字段不在 GROUP BY 中
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SELECT
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department,
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name, -- 错误!name 未分组
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AVG(salary)
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FROM employees
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GROUP BY department
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-- 解决1:添加到 GROUP BY
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SELECT
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department,
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name,
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AVG(salary)
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FROM employees
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GROUP BY department, name
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-- 解决2:使用聚合函数处理
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SELECT
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department,
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collect_list(name) AS names, -- 收集所有name
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AVG(salary)
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FROM employees
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GROUP BY department
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```
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### 问题2:NULL 影响聚合
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```sql
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-- COUNT(*) 包含 NULL 行
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-- COUNT(col) 不包含 NULL
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SELECT
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COUNT(*) AS total, -- 包含 NULL 行
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COUNT(amount) AS valid, -- 不包含 amount 为 NULL 的行
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COUNT(DISTINCT amount) AS unique_values
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FROM orders
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-- SUM/AVG/MIN/MAX 自动忽略 NULL
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SELECT AVG(price) FROM products -- NULL 自动排除
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```
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### 问题3:聚合结果精度
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```sql
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-- AVG 可能精度丢失
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SELECT
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AVG(amount) AS avg_amount -- 可能精度不够
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AVG(CAST(amount AS DECIMAL(18,6))) AS precise_avg -- 高精度
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FROM orders
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-- ROUND 控制精度
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SELECT
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ROUND(AVG(amount), 2) AS avg_amount
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FROM orders
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```
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---
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## 聚合性能优化
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```sql
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-- 1. 先过滤再聚合
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SELECT
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department,
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COUNT(*) AS count
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FROM employees
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WHERE hire_date >= '2024-01-01' -- 先过滤
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GROUP BY department
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-- 2. 大数据量用近似聚合
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SELECT
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approx_count_distinct(user_id) AS users -- 比 COUNT(DISTINCT) 快
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FROM orders
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-- 3. 减少分组字段数量
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SELECT
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category, -- 减少分组字段
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COUNT(*) AS count
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FROM products
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GROUP BY category -- 比 GROUP BY category, brand 快
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-- 4. 避免复杂计算在 GROUP BY 前
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SELECT
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department,
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AVG(salary * 1.1) AS adjusted_avg -- 先计算再聚合
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FROM employees
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GROUP BY department
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```
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---
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## 聚合模式选择指南
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| 需求 | 推荐方式 |
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|------|----------|
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| 简单统计 | GROUP BY + 聚合函数 |
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| 分条件统计 | CASE WHEN + SUM/COUNT |
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| 去重计数 | COUNT(DISTINCT) |
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| 大数据去重 | approx_count_distinct |
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| 收集数组 | collect_list / collect_set |
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| 层级汇总 | ROLLUP |
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| 全维度汇总 | CUBE |
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| 自定义组合 | GROUPING SETS |
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| 分组内计算 | 窗口函数 |
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| 多条件过滤 | HAVING |
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@@ -0,0 +1,320 @@
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# Apache Doris SQL 语法参考
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## 数据类型
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| 类型 | 说明 | 示例 |
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|------|------|------|
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| BOOLEAN | 布尔 | active BOOLEAN |
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| TINYINT | 1字节整数 | level TINYINT |
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| SMALLINT | 2字节整数 | age SMALLINT |
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| INT | 4字节整数 | count INT |
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| BIGINT | 8字节整数 | id BIGINT |
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| LARGEINT | 16字节整数 | hash_key LARGEINT |
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| FLOAT | 4字节浮点 | score FLOAT |
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| DOUBLE | 8字节浮点 | price DOUBLE |
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| DECIMAL(p,s) | 定点数 | amount DECIMAL(18,2) |
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| DATE | 日期 | birth_date DATE |
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| DATETIME | 日期时间(精确到秒) | created_at DATETIME |
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| CHAR(n) | 定长字符串 | code CHAR(10) |
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| VARCHAR(n) | 变长字符串 | name VARCHAR(100) |
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| STRING | 变长字符串(无长度限制) | description STRING |
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| BITMAP | 位图(精确去重) | user_bitmap BITMAP |
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| HLL | HyperLogLog(近似去重) | user_hll HLL |
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| JSON | JSON 数据 | props JSON |
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| ARRAY\<type\> | 数组 | tags ARRAY\<STRING\> |
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| MAP\<k,v\> | 映射 | props MAP\<STRING,STRING\> |
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| STRUCT\<field:type,...\> | 结构体 | info STRUCT\<id:INT,name:STRING\> |
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---
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## 时间函数
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```sql
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-- 当前时间
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NOW() -- 当前日期时间
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CURDATE() -- 当前日期
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CURRENT_TIMESTAMP() -- 当前时间戳
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-- 格式转换
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DATE_FORMAT(date_col, '%Y-%m-%d') -- 日期格式化
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DATE_FORMAT(datetime_col, '%Y-%m-%d %H:%i:%s') -- 时间格式化
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STR_TO_DATE(str, '%Y-%m-%d') -- 字符串转日期
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-- 日期计算
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DATE_ADD(date_col, INTERVAL 7 DAY) -- 加7天
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DATE_SUB(date_col, INTERVAL 7 DAY) -- 减7天
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DATEDIFF(end_date, start_date) -- 日期差(天数)
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TIMESTAMPDIFF(unit, start, end) -- 时间差(指定单位)
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TIMESTAMPADD(unit, interval, datetime) -- 时间加
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-- 日期提取
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YEAR(date_col) -- 年
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MONTH(date_col) -- 月
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DAY(date_col) -- 日
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HOUR(datetime_col) -- 时
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MINUTE(datetime_col) -- 分
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SECOND(datetime_col) -- 秒
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QUARTER(date_col) -- 季度 (1-4)
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WEEK(date_col) -- 年中第几周
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DAYOFWEEK(date_col) -- 周几 (1=周日)
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DAYOFYEAR(date_col) -- 年中第几天
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|
||||
-- Unix 时间戳
|
||||
UNIX_TIMESTAMP() -- 当前 Unix 时间戳
|
||||
UNIX_TIMESTAMP(datetime_col) -- 转换为 Unix 时间戳
|
||||
FROM_UNIXTIME(timestamp) -- Unix 时间戳转时间字符串
|
||||
FROM_UNIXTIME(timestamp, fmt) -- 带格式的转换
|
||||
|
||||
-- Doris 日期格式符(不同于 Spark)
|
||||
-- %Y: 4位年, %m: 2位月, %d: 2位日
|
||||
-- %H: 24小时制, %i: 分钟, %s: 秒
|
||||
-- %j: 年中天数, %W: 周名
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## 字符串函数
|
||||
|
||||
```sql
|
||||
-- 常用函数
|
||||
CONCAT(str1, str2, ...) -- 字符串拼接
|
||||
CONCAT_WS('-', str1, str2, ...) -- 用分隔符拼接
|
||||
LOWER(str) -- 转小写
|
||||
UPPER(str) -- 转大写
|
||||
TRIM(str) -- 去两端空格
|
||||
LTRIM(str) -- 去左空格
|
||||
RTRIM(str) -- 去右空格
|
||||
LENGTH(str) -- 字符串长度
|
||||
CHAR_LENGTH(str) -- 字符数(中文友好)
|
||||
SUBSTRING(str, pos, len) -- 截取字符串(pos从1开始)
|
||||
LEFT(str, len) -- 取左边len个字符
|
||||
RIGHT(str, len) -- 取右边len个字符
|
||||
REVERSE(str) -- 反转字符串
|
||||
REPEAT(str, n) -- 重复n次
|
||||
SPACE(n) -- 生成n个空格
|
||||
|
||||
-- 查找与替换
|
||||
INSTR(str, substr) -- 查找子串位置
|
||||
LOCATE(substr, str, pos) -- 从pos位置查找
|
||||
REPLACE(str, old, new) -- 替换
|
||||
REGEXP_EXTRACT(str, pattern, idx) -- 正则提取(注意和 Spark 参数不同)
|
||||
REGEXP_REPLACE(str, pattern, replacement) -- 正则替换
|
||||
|
||||
-- 分割
|
||||
SPLIT_BY_STRING(str, delimiter) -- 分割(Doris 特有)
|
||||
SPLIT_PART(str, delimiter, idx) -- 取分割后的第idx部分
|
||||
|
||||
-- 其他
|
||||
INITCAP(str) -- 首字母大写
|
||||
LPAD(str, len, pad) -- 左填充
|
||||
RPAD(str, len, pad) -- 右填充
|
||||
HEX(str) -- 转16进制
|
||||
UNHEX(str) -- 16进制转字符串
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## 聚合函数
|
||||
|
||||
```sql
|
||||
-- 基础聚合
|
||||
COUNT(*) -- 计数(含NULL行)
|
||||
COUNT(col) -- 计数(不含NULL)
|
||||
COUNT(DISTINCT col) -- 去重计数
|
||||
SUM(col) -- 求和
|
||||
AVG(col) -- 平均值
|
||||
MIN(col) -- 最小值
|
||||
MAX(col) -- 最大值
|
||||
|
||||
-- 集合聚合
|
||||
GROUP_CONCAT(col SEPARATOR ',') -- 字符串聚合(类似 collect_list)
|
||||
APPROX_COUNT_DISTINCT(col) -- 近似去重计数
|
||||
|
||||
-- 统计函数
|
||||
VARIANCE(col) -- 方差
|
||||
VAR_POP(col) -- 总体方差
|
||||
VAR_SAMP(col) -- 样本方差
|
||||
STDDEV(col) -- 标准差
|
||||
STDDEV_POP(col) -- 总体标准差
|
||||
STDDEV_SAMP(col) -- 样本标准差
|
||||
|
||||
-- Bitmap 精确去重(Doris 特有)
|
||||
-- 用于 Aggregate Key 模型中定义为 BITMAP 的列
|
||||
-- bitmap_union_count(bitmap_col) -- 精确去重计数
|
||||
-- bitmap_union(bitmap_col) -- 合并 bitmap
|
||||
-- bitmap_hash(col) -- 将值转为 bitmap(用于写入)
|
||||
|
||||
-- HLL 近似去重(Doris 特有)
|
||||
-- hll_union_agg(hll_col) -- 近似去重计数
|
||||
-- hll_cardinality(hll_col) -- 返回 HLL 基数
|
||||
-- hll_hash(col) -- 将值转为 HLL(用于写入)
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## 条件表达式
|
||||
|
||||
```sql
|
||||
-- CASE WHEN
|
||||
CASE
|
||||
WHEN condition1 THEN result1
|
||||
WHEN condition2 THEN result2
|
||||
ELSE default_result
|
||||
END
|
||||
|
||||
-- CASE 字段匹配
|
||||
CASE field
|
||||
WHEN value1 THEN result1
|
||||
WHEN value2 THEN result2
|
||||
ELSE default_result
|
||||
END
|
||||
|
||||
-- COALESCE(取第一个非空值)
|
||||
COALESCE(col1, col2, default_value)
|
||||
|
||||
-- NULLIF(相等返回NULL)
|
||||
NULLIF(col1, col2)
|
||||
|
||||
-- IF(简单条件)
|
||||
IF(condition, true_value, false_value)
|
||||
|
||||
-- IFNULL(空值替换,等同 NVL)
|
||||
IFNULL(col, default_value)
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## JSON 函数
|
||||
|
||||
```sql
|
||||
-- 解析与提取
|
||||
JSON_PARSE(json_str) -- 解析 JSON 字符串
|
||||
JSON_EXTRACT(json_str, '$.field') -- 提取 JSON 字段(返回 JSON 类型)
|
||||
JSON_EXTRACT_STRING(json_str, '$.field') -- 提取 JSON 字段(返回 STRING)
|
||||
JSON_EXTRACT_INT(json_str, '$.field') -- 提取 JSON 字段(返回 INT)
|
||||
JSON_EXTRACT_DOUBLE(json_str, '$.field') -- 提取 JSON 字段(返回 DOUBLE)
|
||||
JSON_EXTRACT_BOOL(json_str, '$.field') -- 提取 JSON 字段(返回 BOOLEAN)
|
||||
|
||||
-- 路径语法
|
||||
-- $ : 根节点
|
||||
-- $.field : 对象字段
|
||||
-- $[0] : 数组索引
|
||||
-- $.a.b : 嵌套字段
|
||||
|
||||
-- 构造
|
||||
JSON_OBJECT('key1', val1, 'key2', val2) -- 构造 JSON 对象
|
||||
JSON_ARRAY(val1, val2, ...) -- 构造 JSON 数组
|
||||
|
||||
-- 查询
|
||||
JSON_LENGTH(json_str) -- JSON 长度
|
||||
JSON_KEYS(json_str) -- JSON 所有 key
|
||||
JSON_VALID(json_str) -- 是否合法 JSON
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## ARRAY 函数
|
||||
|
||||
```sql
|
||||
-- 创建
|
||||
ARRAY(val1, val2, ...) -- 创建数组
|
||||
|
||||
-- 访问
|
||||
array_contains(arr, val) -- 判断是否包含
|
||||
element_at(arr, idx) -- 取元素(idx从1开始)
|
||||
arr[idx] -- 取元素(idx从0开始)
|
||||
|
||||
-- 操作
|
||||
SIZE(arr) -- 数组长度
|
||||
ARRAY_JOIN(arr, delimiter) -- 数组转字符串
|
||||
CONCAT(arr1, arr2) -- 数组拼接
|
||||
|
||||
-- 展开与排序
|
||||
EXPLODE(arr) -- 展开数组为多行(LATERAL VIEW 中使用)
|
||||
ARRAY_SORT(arr) -- 排序
|
||||
ARRAY_DISTINCT(arr) -- 去重
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## 与 Spark SQL 的主要差异
|
||||
|
||||
| 特性 | Spark SQL | Apache Doris | 说明 |
|
||||
|------|-----------|-------------|------|
|
||||
| **日期格式符** | `yyyy-MM-dd` | `%Y-%m-%d` | Doris 用 MySQL 风格格式符 |
|
||||
| **当前时间** | `current_timestamp()` | `NOW()` 或 `CURRENT_TIMESTAMP()` | 都支持,Doris 偏好 NOW() |
|
||||
| **日期加减** | `date_add(col, 7)` | `DATE_ADD(col, INTERVAL 7 DAY)` | Doris 需要 INTERVAL 语法 |
|
||||
| **正则提取** | `regexp_extract(str, pattern, idx)` | `REGEXP_EXTRACT(str, pattern, idx)` | 参数名可能不同 |
|
||||
| **LEFT SEMI JOIN** | ✅ 支持 | ❌ 不支持 | 用 IN 子查询替代 |
|
||||
| **LEFT ANTI JOIN** | ✅ 支持 | ❌ 不支持 | 用 NOT IN / NOT EXISTS 替代 |
|
||||
| **INSERT OVERWRITE** | ✅ 支持 | ✅ 2.0+ 支持 | 早期版本不支持 |
|
||||
| **CTE (WITH)** | ✅ 支持 | ✅ 支持 | 都支持 |
|
||||
| **MERGE INTO** | ✅ 支持 | ❌ 不支持 | Doris 用 UPSERT 替代 |
|
||||
| **临时表链式处理** | ✅ 推荐 | ✅ 统一规范 | 编码规范层面统一禁止 CTE |
|
||||
| **精确去重** | COUNT(DISTINCT) | COUNT(DISTINCT) 或 BITMAP | Doris BITMAP 性能更好 |
|
||||
| **近似去重** | `approx_count_distinct` | HLL 类型 | Doris 内置 HLL 类型 |
|
||||
| **UPDATE/DELETE** | ❌ 不支持 | ✅ 支持 | Doris 支持 DML |
|
||||
| **UPSERT** | ❌ 不支持 | ❌ 不直接支持 | 用 Aggregate/Unique Key 模型替代 |
|
||||
| **分页** | LIMIT(无OFFSET) | LIMIT + OFFSET | Doris 完整支持 |
|
||||
| **JSON** | `get_json_object` | `JSON_EXTRACT_STRING` 等系列函数 | 函数名完全不同 |
|
||||
| **collect_list/set** | ✅ 支持 | ❌ 不直接支持 | 用 GROUP_CONCAT 替代 |
|
||||
| **LATERAL VIEW explode** | ✅ 支持 | ✅ 支持 | 语法兼容 |
|
||||
|
||||
---
|
||||
|
||||
## SQL 生成规则
|
||||
|
||||
### 通用规则(所有引擎统一)
|
||||
|
||||
1. **禁止使用 CTE (WITH 子句)**,每个主要逻辑步骤必须物化为临时表
|
||||
2. **先 DROP 再 CREATE**:`DROP TABLE IF EXISTS ...; CREATE TABLE ... AS SELECT ...;`
|
||||
3. **禁止 `SELECT *`**,必须明确列出所有字段
|
||||
4. 多表查询时所有表必须使用简短别名
|
||||
5. 每个步骤前添加注释说明
|
||||
6. **谓词下推**:过滤条件前置,JOIN 时在 WHERE 中一并添加过滤
|
||||
7. 临时表命名:`${db_tmp_env}.tmp_{业务简称}_{步骤序号}`
|
||||
|
||||
### Doris 特有规则
|
||||
|
||||
1. 使用 `INSERT INTO` 写入目标表(Doris 2.0+ 也支持 `INSERT OVERWRITE`)
|
||||
2. Aggregate Key 表自动合并相同 Key 的数据
|
||||
3. Unique Key 表自动按主键去重,保留最新数据
|
||||
4. 不支持 `LEFT SEMI JOIN` / `LEFT ANTI JOIN`,用 `IN` / `NOT IN` 替代
|
||||
5. 精确去重推荐 `BITMAP`,近似去重推荐 `HLL`
|
||||
6. 日期函数用 MySQL 风格:
|
||||
- `DATE_FORMAT(col, '%Y-%m-%d')`(不是 `yyyy-MM-dd`)
|
||||
- `DATE_ADD(col, INTERVAL 7 DAY)`(不是 `date_add(col, 7)`)
|
||||
- `CURDATE()` / `NOW()`
|
||||
7. 不支持 `collect_list` / `collect_set`,用 `GROUP_CONCAT` 替代
|
||||
8. 时间范围筛选:
|
||||
```sql
|
||||
-- 日账期过滤
|
||||
WHERE stat_date = '${day_id}'
|
||||
-- 最近N个月
|
||||
WHERE stat_date >= DATE_FORMAT(DATE_SUB(STR_TO_DATE('${month_id}', '%Y%m'), INTERVAL N MONTH), '%Y%m')
|
||||
AND stat_date < '${month_id}'
|
||||
```
|
||||
|
||||
### SQL 脚本结构
|
||||
|
||||
```sql
|
||||
-- =====================================================================
|
||||
-- @SqlName: doris-D-SQL-{表名}
|
||||
-- @Engine: doris
|
||||
-- ...(头注释)
|
||||
-- =====================================================================
|
||||
|
||||
-- Step01: {步骤描述}
|
||||
DROP TABLE IF EXISTS ${db_tmp_env}.tmp_xxx_01;
|
||||
CREATE TABLE ${db_tmp_env}.tmp_xxx_01 AS
|
||||
SELECT ...;
|
||||
|
||||
-- Step02: {步骤描述}
|
||||
DROP TABLE IF EXISTS ${db_tmp_env}.tmp_xxx_02;
|
||||
CREATE TABLE ${db_tmp_env}.tmp_xxx_02 AS
|
||||
SELECT ...;
|
||||
|
||||
-- 最后一步:写入目标表
|
||||
INSERT INTO ${db_eda_env}.target_table
|
||||
SELECT ...;
|
||||
```
|
||||
@@ -0,0 +1,334 @@
|
||||
# Hive SQL 语法参考
|
||||
|
||||
## 数据类型
|
||||
|
||||
| 类型 | 说明 | 示例 |
|
||||
|------|------|------|
|
||||
| TINYINT | 1字节整数 | level TINYINT |
|
||||
| SMALLINT | 2字节整数 | age SMALLINT |
|
||||
| INT | 4字节整数 | count INT |
|
||||
| BIGINT | 8字节整数 | id BIGINT |
|
||||
| FLOAT | 4字节浮点 | score FLOAT |
|
||||
| DOUBLE | 8字节浮点 | price DOUBLE |
|
||||
| DECIMAL(p,s) | 定点数 | amount DECIMAL(18,2) |
|
||||
| BOOLEAN | 布尔 | active BOOLEAN |
|
||||
| STRING | 变长字符串 | name STRING |
|
||||
| VARCHAR(n) | 变长字符串(限长) | code VARCHAR(50) |
|
||||
| CHAR(n) | 定长字符串 | flag CHAR(1) |
|
||||
| DATE | 日期 | birth_date DATE |
|
||||
| TIMESTAMP | 时间戳(纳秒精度) | created_at TIMESTAMP |
|
||||
| BINARY | 二进制 | data BINARY |
|
||||
| ARRAY\<type\> | 数组 | tags ARRAY\<STRING\> |
|
||||
| MAP\<k,v\> | 映射 | props MAP\<STRING,STRING\> |
|
||||
| STRUCT\<f1:t1,...\> | 结构体 | user STRUCT\<id:INT,name:STRING\> |
|
||||
| UNIONTYPE\<t1,t2,...\> | 联合类型 | value UNIONTYPE\<INT,STRING\> |
|
||||
|
||||
---
|
||||
|
||||
## 时间函数
|
||||
|
||||
```sql
|
||||
-- 当前时间
|
||||
current_date() -- 当前日期
|
||||
current_timestamp() -- 当前时间戳
|
||||
unix_timestamp() -- 当前 Unix 时间戳(秒)
|
||||
|
||||
-- 格式转换
|
||||
date_format(date_col, 'yyyy-MM-dd') -- 日期格式化
|
||||
date_format(timestamp_col, 'yyyy-MM-dd HH:mm:ss') -- 时间格式化
|
||||
to_date(string_col) -- 字符串转日期
|
||||
to_date(string_col, 'yyyy-MM-dd') -- 字符串转日期(带格式)
|
||||
from_unixtime(timestamp) -- Unix 时间戳转字符串
|
||||
from_unixtime(timestamp, 'yyyy-MM-dd') -- 带格式转换
|
||||
|
||||
-- 日期计算
|
||||
date_add(date_col, 7) -- 加7天
|
||||
date_sub(date_col, 7) -- 减7天
|
||||
add_months(date_col, 3) -- 加3个月
|
||||
datediff(end_date, start_date) -- 日期差(天数)
|
||||
months_between(date1, date2) -- 月份差
|
||||
|
||||
-- 日期提取
|
||||
year(date_col) -- 年
|
||||
month(date_col) -- 月
|
||||
day(date_col) -- 日
|
||||
dayofmonth(date_col) -- 月中第几天
|
||||
dayofweek(date_col) -- 周几 (1=周日, 7=周六)
|
||||
hour(timestamp_col) -- 时
|
||||
minute(timestamp_col) -- 分
|
||||
second(timestamp_col) -- 秒
|
||||
quarter(date_col) -- 季度 (1-4)
|
||||
weekofyear(date_col) -- 年中第几周
|
||||
last_day(date_col) -- 月末日期
|
||||
trunc(date_col, 'MM') -- 月初日期
|
||||
trunc(date_col, 'YY') -- 年初日期
|
||||
|
||||
-- Unix 时间戳
|
||||
unix_timestamp(date_col) -- 转 Unix 时间戳
|
||||
unix_timestamp(string_col, 'yyyy-MM-dd') -- 指定格式转换
|
||||
from_unixtime(timestamp) -- Unix 时间戳转字符串
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## 字符串函数
|
||||
|
||||
```sql
|
||||
-- 常用函数
|
||||
concat(str1, str2, ...) -- 字符串拼接
|
||||
concat_ws('-', str1, str2, ...) -- 用分隔符拼接
|
||||
lower(str) -- 转小写
|
||||
upper(str) -- 转大写
|
||||
trim(str) -- 去两端空格
|
||||
ltrim(str) -- 去左空格
|
||||
rtrim(str) -- 去右空格
|
||||
length(str) -- 字符串长度
|
||||
substring(str, pos, len) -- 截取字符串(pos从1开始)
|
||||
substr(str, pos, len) -- 同 substring
|
||||
left(str, len) -- 取左边len个字符
|
||||
right(str, len) -- 取右边len个字符
|
||||
reverse(str) -- 反转字符串
|
||||
repeat(str, n) -- 重复n次
|
||||
space(n) -- 生成n个空格
|
||||
|
||||
-- 查找与替换
|
||||
instr(str, substr) -- 查找子串位置
|
||||
locate(substr, str, pos) -- 从pos位置查找
|
||||
replace(str, old, new) -- 替换
|
||||
regexp_extract(str, pattern, idx) -- 正则提取
|
||||
regexp_replace(str, pattern, replacement) -- 正则替换
|
||||
|
||||
-- 分割
|
||||
split(str, delimiter) -- 分割成数组
|
||||
|
||||
-- 其他
|
||||
initcap(str) -- 首字母大写
|
||||
lpad(str, len, pad) -- 左填充
|
||||
rpad(str, len, pad) -- 右填充
|
||||
hex(col) -- 转16进制
|
||||
unhex(str) -- 16进制转字符串
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## 聚合函数
|
||||
|
||||
```sql
|
||||
-- 基础聚合
|
||||
COUNT(*) -- 计数(含NULL行)
|
||||
COUNT(col) -- 计数(不含NULL)
|
||||
COUNT(DISTINCT col) -- 去重计数
|
||||
SUM(col) -- 求和
|
||||
AVG(col) -- 平均值
|
||||
MIN(col) -- 最小值
|
||||
MAX(col) -- 最大值
|
||||
|
||||
-- 集合聚合
|
||||
collect_list(col) -- 返回数组(不去重)
|
||||
collect_set(col) -- 返回数组(去重)
|
||||
|
||||
-- 统计函数
|
||||
variance(col) -- 方差
|
||||
var_pop(col) -- 总体方差
|
||||
var_samp(col) -- 样本方差
|
||||
stddev(col) -- 标准差
|
||||
stddev_pop(col) -- 总体标准差
|
||||
stddev_samp(col) -- 样本标准差
|
||||
|
||||
-- 近似函数
|
||||
approx_count_distinct(col) -- 近似去重计数(大数据量优化)
|
||||
|
||||
-- 其他
|
||||
first(col) -- 第一个值
|
||||
last(col) -- 最后一个值
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## 条件表达式
|
||||
|
||||
```sql
|
||||
-- CASE WHEN
|
||||
CASE
|
||||
WHEN condition1 THEN result1
|
||||
WHEN condition2 THEN result2
|
||||
ELSE default_result
|
||||
END
|
||||
|
||||
-- CASE 字段匹配
|
||||
CASE field
|
||||
WHEN value1 THEN result1
|
||||
WHEN value2 THEN result2
|
||||
ELSE default_result
|
||||
END
|
||||
|
||||
-- COALESCE(取第一个非空值)
|
||||
COALESCE(col1, col2, default_value)
|
||||
|
||||
-- NULLIF(相等返回NULL)
|
||||
NULLIF(col1, col2)
|
||||
|
||||
-- IF(简单条件)
|
||||
IF(condition, true_value, false_value)
|
||||
|
||||
-- NVL(空值替换)
|
||||
NVL(col, default_value)
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## 复杂类型操作
|
||||
|
||||
```sql
|
||||
-- ARRAY 操作
|
||||
array(val1, val2, ...) -- 创建数组
|
||||
array_contains(arr, val) -- 判断是否包含
|
||||
element_at(arr, idx) -- 取元素(idx从1开始)
|
||||
arr[idx] -- 取元素(idx从0开始)
|
||||
size(arr) -- 数组长度
|
||||
array_join(arr, delimiter) -- 数组转字符串
|
||||
sort_array(arr) -- 排序
|
||||
array_distinct(arr) -- 去重
|
||||
|
||||
-- 展开(LATERAL VIEW + explode)
|
||||
-- 展开数组
|
||||
SELECT id, tag
|
||||
FROM table
|
||||
LATERAL VIEW explode(tags) t AS tag;
|
||||
|
||||
-- 展开数组带索引
|
||||
SELECT id, pos, tag
|
||||
FROM table
|
||||
LATERAL VIEW posexplode(tags) t AS pos, tag;
|
||||
|
||||
-- 展开 Map
|
||||
SELECT id, map_key, map_value
|
||||
FROM table
|
||||
LATERAL VIEW explode(props) m AS map_key, map_value;
|
||||
|
||||
-- MAP 操作
|
||||
map(key1, val1, key2, val2) -- 创建 Map
|
||||
str_to_map(str, delim1, delim2) -- 字符串转 Map
|
||||
map_contains(map, key) -- 判断是否包含key
|
||||
map_keys(map) -- 所有 key(返回数组)
|
||||
map_values(map) -- 所有 value(返回数组)
|
||||
size(map) -- Map大小
|
||||
|
||||
-- STRUCT 操作
|
||||
named_struct('name1', val1, 'name2', val2) -- 创建结构体
|
||||
struct_col.field_name -- 访问结构体字段
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## 分区表操作
|
||||
|
||||
```sql
|
||||
-- 创建分区表
|
||||
CREATE TABLE target_table (
|
||||
id BIGINT,
|
||||
name STRING,
|
||||
amount DECIMAL(18,2)
|
||||
)
|
||||
PARTITIONED BY (day_id STRING)
|
||||
STORED AS ORC;
|
||||
|
||||
-- 静态分区写入
|
||||
INSERT OVERWRITE TABLE target_table
|
||||
PARTITION (day_id = '${day_id}')
|
||||
SELECT id, name, amount FROM source_table;
|
||||
|
||||
-- 动态分区写入
|
||||
SET hive.exec.dynamic.partition = true;
|
||||
SET hive.exec.dynamic.partition.mode = nonstrict;
|
||||
|
||||
INSERT OVERWRITE TABLE target_table
|
||||
PARTITION (day_id)
|
||||
SELECT id, name, amount, day_id FROM source_table;
|
||||
|
||||
-- 分区管理
|
||||
SHOW PARTITIONS target_table;
|
||||
ALTER TABLE target_table ADD IF NOT EXISTS PARTITION (day_id = '2026-05-10');
|
||||
ALTER TABLE target_table DROP IF EXISTS PARTITION (day_id = '2026-01-01');
|
||||
|
||||
-- MSCK REPAIR(恢复分区元数据)
|
||||
MSCK REPAIR TABLE target_table;
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## 与 Spark SQL 的主要差异
|
||||
|
||||
| 特性 | Spark SQL | Hive | 说明 |
|
||||
|------|-----------|------|------|
|
||||
| **LEFT SEMI JOIN** | ✅ 独立语法 | ✅ 支持(语义相同) | Hive 也可用 IN 子查询替代 |
|
||||
| **LEFT ANTI JOIN** | ✅ 独立语法 | ✅ 支持(语义相同) | Hive 也可用 NOT IN 替代 |
|
||||
| **CTE (WITH)** | ✅ 支持 | ✅ Hive 0.13+ 支持 | 都支持但 Hive 中推荐物化临时表 |
|
||||
| **INSERT OVERWRITE** | ✅ 支持 | ✅ 支持 | 写法一致 |
|
||||
| **MERGE INTO** | ✅ 支持 | ❌ 不支持 | Hive 不支持 |
|
||||
| **UPDATE/DELETE** | ❌ 不支持 | 仅 ACID 表支持 | 普通 Hive 表不支持 |
|
||||
| **collect_list/set** | ✅ 支持 | ✅ 支持 | 完全一致 |
|
||||
| **LATERAL VIEW** | ✅ 支持 | ✅ 支持(Hive 原生) | Hive 首创的语法 |
|
||||
| **分桶 JOIN** | 可优化 | 可优化(SMB JOIN) | Hive 分桶优化更成熟 |
|
||||
| **日期格式** | `yyyy-MM-dd` | `yyyy-MM-dd` | 格式一致 |
|
||||
| **临时表** | CREATE TEMP TABLE | CREATE TEMPORARY TABLE | 关键字略有不同 |
|
||||
| **存储格式** | PARQUET/ORC | ORC/PARQUET/TEXTFILE | Hive 支持 TEXTFILE |
|
||||
| **分区发现** | 自动 | 需 MSCK REPAIR 或 ALTER | Hive 需手动恢复 |
|
||||
| **复杂类型** | 完整支持 | 完整支持 | 基本一致 |
|
||||
| **窗口函数** | ✅ 完整支持 | ✅ 完整支持 | 语法一致 |
|
||||
|
||||
---
|
||||
|
||||
## SQL 生成规则
|
||||
|
||||
### 通用规则(所有引擎统一)
|
||||
|
||||
1. **禁止使用 CTE (WITH 子句)**,每个主要逻辑步骤必须物化为临时表
|
||||
2. **先 DROP 再 CREATE**:`DROP TABLE IF EXISTS ...; CREATE TABLE ... AS SELECT ...;`
|
||||
3. **禁止 `SELECT *`**,必须明确列出所有字段
|
||||
4. 多表查询时所有表必须使用简短别名
|
||||
5. 每个步骤前添加注释说明
|
||||
6. **谓词下推**:过滤条件前置,JOIN 时在 WHERE 中一并添加过滤
|
||||
7. 临时表命名:`${db_tmp_env}.tmp_{业务简称}_{步骤序号}`
|
||||
|
||||
### Hive 特有规则
|
||||
|
||||
1. 使用 `INSERT OVERWRITE TABLE ... PARTITION (...)` 写入目标表
|
||||
2. 动态分区需先 `SET hive.exec.dynamic.partition = true;`
|
||||
3. 分区列不能出现在表定义的列中(Hive 特有约束)
|
||||
4. 支持 `collect_list` / `collect_set` 聚合
|
||||
5. 支持 `LATERAL VIEW explode()` 展开数组
|
||||
6. 日期函数:`date_format()`, `to_date()`, `date_add()`, `add_months()`(和 Spark 一致)
|
||||
7. 时间范围筛选:
|
||||
```sql
|
||||
-- 日账期过滤
|
||||
WHERE day_id = '${day_id}'
|
||||
-- 最近N个月(月份格式 yyyyMM)
|
||||
WHERE month_id >= date_format(add_months(to_date('${month_id}', 'yyyyMM'), -N), 'yyyyMM')
|
||||
AND month_id < '${month_id}'
|
||||
```
|
||||
|
||||
### SQL 脚本结构
|
||||
|
||||
```sql
|
||||
-- =====================================================================
|
||||
-- @SqlName: hive-D-SQL-{表名}
|
||||
-- @Engine: hive
|
||||
-- ...(头注释)
|
||||
-- =====================================================================
|
||||
|
||||
-- Step01: {步骤描述}
|
||||
DROP TABLE IF EXISTS ${db_tmp_env}.tmp_xxx_01;
|
||||
CREATE TABLE ${db_tmp_env}.tmp_xxx_01 AS
|
||||
SELECT ...;
|
||||
|
||||
-- Step02: {步骤描述}
|
||||
DROP TABLE IF EXISTS ${db_tmp_env}.tmp_xxx_02;
|
||||
CREATE TABLE ${db_tmp_env}.tmp_xxx_02 AS
|
||||
SELECT ...;
|
||||
|
||||
-- 最后一步:写入目标表
|
||||
INSERT OVERWRITE TABLE ${db_eda_env}.target_table
|
||||
PARTITION (day_id = '${day_id}')
|
||||
SELECT ...;
|
||||
```
|
||||
@@ -0,0 +1,369 @@
|
||||
# JOIN 模式速查
|
||||
|
||||
## JOIN 类型
|
||||
|
||||
| 类型 | 说明 | 结果特点 |
|
||||
|------|------|----------|
|
||||
| INNER JOIN | 内连接 | 只返回匹配的行 |
|
||||
| LEFT JOIN | 左外连接 | 左表全部,右表匹配(无匹配为NULL) |
|
||||
| RIGHT JOIN | 右外连接 | 右表全部,左表匹配(无匹配为NULL) |
|
||||
| FULL OUTER JOIN | 全外连接 | 两表全部,无匹配处为NULL |
|
||||
| CROSS JOIN | 交叉连接 | 笛卡尔积(每行与每行组合) |
|
||||
| LEFT SEMI JOIN | 左半连接 | 左表中在右表有匹配的行(不返回右表列) |
|
||||
| LEFT ANTI JOIN | 左反连接 | 左表中在右表无匹配的行 |
|
||||
|
||||
---
|
||||
|
||||
## INNER JOIN
|
||||
|
||||
```sql
|
||||
-- 基本语法
|
||||
SELECT a.*, b.*
|
||||
FROM table_a a
|
||||
INNER JOIN table_b b ON a.id = b.id
|
||||
|
||||
-- 等价写法(逗号连接)
|
||||
SELECT a.*, b.*
|
||||
FROM table_a a, table_b b
|
||||
WHERE a.id = b.id
|
||||
|
||||
-- 多字段关联
|
||||
SELECT a.*, b.*
|
||||
FROM table_a a
|
||||
INNER JOIN table_b b
|
||||
ON a.user_id = b.user_id
|
||||
AND a.order_date = b.order_date
|
||||
```
|
||||
|
||||
**使用场景**:只需要两表都有匹配的数据时使用。
|
||||
|
||||
---
|
||||
|
||||
## LEFT JOIN
|
||||
|
||||
```sql
|
||||
-- 基本语法
|
||||
SELECT a.*, b.*
|
||||
FROM table_a a
|
||||
LEFT JOIN table_b b ON a.id = b.id
|
||||
|
||||
-- 处理右表NULL值
|
||||
SELECT
|
||||
a.id,
|
||||
a.name,
|
||||
COALESCE(b.amount, 0) AS amount, -- NULL转0
|
||||
IF(b.id IS NULL, '无匹配', '有匹配') AS match_status
|
||||
FROM table_a a
|
||||
LEFT JOIN table_b b ON a.id = b.id
|
||||
|
||||
-- 找出左表中无匹配的行(差集)
|
||||
SELECT a.*
|
||||
FROM table_a a
|
||||
LEFT JOIN table_b b ON a.id = b.id
|
||||
WHERE b.id IS NULL
|
||||
```
|
||||
|
||||
**使用场景**:保留左表所有数据,右表补充信息时使用。
|
||||
|
||||
---
|
||||
|
||||
## RIGHT JOIN
|
||||
|
||||
```sql
|
||||
-- 基本语法
|
||||
SELECT a.*, b.*
|
||||
FROM table_a a
|
||||
RIGHT JOIN table_b b ON a.id = b.id
|
||||
|
||||
-- 等价于 LEFT JOIN 反过来
|
||||
SELECT a.*, b.*
|
||||
FROM table_b b
|
||||
LEFT JOIN table_a a ON b.id = a.id
|
||||
```
|
||||
|
||||
**使用场景**:保留右表所有数据时使用(可改用 LEFT JOIN 反转)。
|
||||
|
||||
---
|
||||
|
||||
## FULL OUTER JOIN
|
||||
|
||||
```sql
|
||||
-- 基本语法
|
||||
SELECT
|
||||
COALESCE(a.id, b.id) AS id, -- 统一ID
|
||||
a.name,
|
||||
b.amount
|
||||
FROM table_a a
|
||||
FULL OUTER JOIN table_b b ON a.id = b.id
|
||||
|
||||
-- 找出两表差异
|
||||
SELECT
|
||||
a.id AS a_id,
|
||||
b.id AS b_id,
|
||||
CASE
|
||||
WHEN a.id IS NULL THEN '仅在B表'
|
||||
WHEN b.id IS NULL THEN '仅在A表'
|
||||
ELSE '两表都有'
|
||||
END AS status
|
||||
FROM table_a a
|
||||
FULL OUTER JOIN table_b b ON a.id = b.id
|
||||
WHERE a.id IS NULL OR b.id IS NULL
|
||||
```
|
||||
|
||||
**使用场景**:需要两表完整数据,分析差异时使用。
|
||||
|
||||
---
|
||||
|
||||
## CROSS JOIN
|
||||
|
||||
```sql
|
||||
-- 基本语法(笛卡尔积)
|
||||
SELECT a.name, b.color
|
||||
FROM products a
|
||||
CROSS JOIN colors b
|
||||
|
||||
-- 结果:products每行与colors每行组合
|
||||
-- products有10行,colors有5行 → 结果50行
|
||||
|
||||
-- 等价写法
|
||||
SELECT a.name, b.color
|
||||
FROM products a, colors b -- 无WHERE条件
|
||||
```
|
||||
|
||||
**使用场景**:生成所有组合、测试数据生成时使用。
|
||||
|
||||
**注意**:数据量大时慎用,可能产生巨量结果。
|
||||
|
||||
---
|
||||
|
||||
## LEFT SEMI JOIN(Spark SQL 特有)
|
||||
|
||||
```sql
|
||||
-- 基本语法
|
||||
SELECT a.*
|
||||
FROM table_a a
|
||||
LEFT SEMI JOIN table_b b ON a.id = b.id
|
||||
|
||||
-- 效果:返回A表中在B表有匹配的行,不返回B表的列
|
||||
-- 等价于 IN 子查询
|
||||
SELECT a.*
|
||||
FROM table_a a
|
||||
WHERE a.id IN (SELECT id FROM table_b b)
|
||||
```
|
||||
|
||||
**使用场景**:只需要判断左表是否在右表存在,不需要右表数据。
|
||||
|
||||
---
|
||||
|
||||
## LEFT ANTI JOIN(Spark SQL 特有)
|
||||
|
||||
```sql
|
||||
-- 基本语法
|
||||
SELECT a.*
|
||||
FROM table_a a
|
||||
LEFT ANTI JOIN table_b b ON a.id = b.id
|
||||
|
||||
-- 效果:返回A表中在B表无匹配的行
|
||||
-- 等价于 NOT IN 子查询
|
||||
SELECT a.*
|
||||
FROM table_a a
|
||||
WHERE a.id NOT IN (SELECT id FROM table_b b)
|
||||
|
||||
-- 或 NOT EXISTS
|
||||
SELECT a.*
|
||||
FROM table_a a
|
||||
WHERE NOT EXISTS (SELECT 1 FROM table_b b WHERE b.id = a.id)
|
||||
```
|
||||
|
||||
**使用场景**:找出差集(左表中不存在于右表的数据)。
|
||||
|
||||
---
|
||||
|
||||
## 多表 JOIN
|
||||
|
||||
```sql
|
||||
-- 三表关联
|
||||
SELECT
|
||||
o.order_id,
|
||||
u.user_name,
|
||||
p.product_name,
|
||||
oi.quantity
|
||||
FROM orders o
|
||||
JOIN users u ON o.user_id = u.id
|
||||
JOIN order_items oi ON o.order_id = oi.order_id
|
||||
JOIN products p ON oi.product_id = p.id
|
||||
|
||||
-- 四表及以上
|
||||
SELECT
|
||||
a.col1,
|
||||
b.col2,
|
||||
c.col3,
|
||||
d.col4
|
||||
FROM table_a a
|
||||
JOIN table_b b ON a.id = b.a_id
|
||||
JOIN table_c c ON b.id = c.b_id
|
||||
JOIN table_d d ON c.id = d.c_id
|
||||
```
|
||||
|
||||
**建议**:多表 JOIN 时,从最小表开始,逐步关联。
|
||||
|
||||
---
|
||||
|
||||
## 自连接(Self Join)
|
||||
|
||||
```sql
|
||||
-- 员工与经理关联
|
||||
SELECT
|
||||
e.name AS employee,
|
||||
m.name AS manager
|
||||
FROM employees e
|
||||
LEFT JOIN employees m ON e.manager_id = m.id
|
||||
|
||||
-- 查找重复数据
|
||||
SELECT
|
||||
a.id,
|
||||
a.name,
|
||||
b.id AS duplicate_id
|
||||
FROM table_a a
|
||||
JOIN table_a b ON a.name = b.name AND a.id < b.id
|
||||
|
||||
-- 紧邻数据比较(前后行)
|
||||
SELECT
|
||||
a.date,
|
||||
a.amount,
|
||||
b.amount AS prev_amount
|
||||
FROM sales a
|
||||
LEFT JOIN sales b ON a.date = b.date + 1
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## JOIN 条件下推优化
|
||||
|
||||
**原则**:过滤条件前置,减少 JOIN 数据量。
|
||||
|
||||
```sql
|
||||
-- 推荐:过滤前置
|
||||
SELECT a.*, b.*
|
||||
FROM table_a a
|
||||
JOIN table_b b ON a.id = b.id
|
||||
WHERE a.date = '${day_id}' -- 先过滤A表
|
||||
AND b.status = 'active' -- 先过滤B表
|
||||
|
||||
-- 不推荐:JOIN后再过滤
|
||||
SELECT a.*, b.*
|
||||
FROM (
|
||||
SELECT * FROM table_a -- 未过滤
|
||||
) a
|
||||
JOIN (
|
||||
SELECT * FROM table_b -- 未过滤
|
||||
) b ON a.id = b.id
|
||||
WHERE a.date = '${day_id}'
|
||||
AND b.status = 'active'
|
||||
```
|
||||
|
||||
**性能差异**:
|
||||
- 推荐:JOIN 前各表已过滤,数据量小,JOIN 快
|
||||
- 不推荐:全表 JOIN 后过滤,数据量大,性能差
|
||||
|
||||
---
|
||||
|
||||
## JOIN 常见问题
|
||||
|
||||
### 问题1:关联字段类型不一致
|
||||
|
||||
```sql
|
||||
-- 错误:STRING 与 BIGINT 关联
|
||||
SELECT a.*, b.*
|
||||
FROM table_a a
|
||||
JOIN table_b b ON a.id = b.id -- a.id是STRING,b.id是BIGINT
|
||||
|
||||
-- 解决:类型转换
|
||||
SELECT a.*, b.*
|
||||
FROM table_a a
|
||||
JOIN table_b b ON CAST(a.id AS BIGINT) = b.id
|
||||
```
|
||||
|
||||
### 问题2:关联字段含NULL
|
||||
|
||||
```sql
|
||||
-- 问题:NULL关联不上
|
||||
SELECT a.*, b.*
|
||||
FROM table_a a
|
||||
LEFT JOIN table_b b ON a.ref_id = b.id -- a.ref_id有NULL
|
||||
|
||||
-- 解决:先过滤NULL或用COALESCE
|
||||
SELECT a.*, b.*
|
||||
FROM table_a a
|
||||
LEFT JOIN table_b b ON COALESCE(a.ref_id, 'N/A') = b.id
|
||||
```
|
||||
|
||||
### 问题3:多字段关联效率低
|
||||
|
||||
```sql
|
||||
-- 问题:多字段关联
|
||||
SELECT a.*, b.*
|
||||
FROM table_a a
|
||||
JOIN table_b b
|
||||
ON a.user_id = b.user_id
|
||||
AND a.order_date = b.order_date
|
||||
AND a.product_id = b.product_id
|
||||
|
||||
-- 解决:合并关联字段
|
||||
SELECT a.*, b.*
|
||||
FROM table_a a
|
||||
JOIN table_b b
|
||||
ON CONCAT(a.user_id, '_', a.order_date, '_', a.product_id)
|
||||
= CONCAT(b.user_id, '_', b.order_date, '_', b.product_id)
|
||||
```
|
||||
|
||||
### 问题4:大表 JOIN 大表
|
||||
|
||||
```sql
|
||||
-- 问题:两表都很大,JOIN 慢
|
||||
SELECT a.*, b.*
|
||||
FROM large_table_a a
|
||||
JOIN large_table_b b ON a.id = b.id
|
||||
|
||||
-- 解决方案:
|
||||
-- 1. 尽量前置过滤
|
||||
-- 2. 使用分区表,按分区关联
|
||||
-- 3. 调整 Spark 并行度
|
||||
-- 4. 使用 BROADCAST JOIN(其中一表较小)
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## BROADCAST JOIN(小表广播)
|
||||
|
||||
```sql
|
||||
-- Spark SQL 自动判断(需配置阈值)
|
||||
-- 小表自动广播到所有节点,避免 Shuffle
|
||||
|
||||
-- 手动指定广播
|
||||
SELECT /*+ BROADCAST(b) */ a.*, b.*
|
||||
FROM large_table_a a
|
||||
JOIN small_table_b b ON a.id = b.id
|
||||
|
||||
-- 多表广播
|
||||
SELECT /*+ BROADCAST(b), BROADCAST(c) */ a.*, b.*, c.*
|
||||
FROM large_table_a a
|
||||
JOIN small_table_b b ON a.id = b.id
|
||||
JOIN small_table_c c ON a.category = c.category
|
||||
```
|
||||
|
||||
**适用条件**:其中一表数据量较小(通常 < 10MB)。
|
||||
|
||||
---
|
||||
|
||||
## JOIN 类型选择指南
|
||||
|
||||
| 需求 | 推荐 JOIN | 说明 |
|
||||
|------|-----------|------|
|
||||
| 两表都有才保留 | INNER JOIN | 最常用 |
|
||||
| 左表全部保留 | LEFT JOIN | 补充右表信息 |
|
||||
| 右表全部保留 | RIGHT JOIN | 或反转用 LEFT JOIN |
|
||||
| 两表全部保留 | FULL OUTER JOIN | 分析差异 |
|
||||
| 判断左表是否在右表存在 | LEFT SEMI JOIN | 不需要右表列 |
|
||||
| 左表不在右表的行 | LEFT ANTI JOIN | 差集查询 |
|
||||
| 生成所有组合 | CROSS JOIN | 慎用 |
|
||||
@@ -0,0 +1,336 @@
|
||||
# Kudu (via Impala) SQL 语法参考
|
||||
|
||||
> **重要**:Kudu 本身没有 SQL 引擎,通过 Impala 访问。本文档是 Impala SQL 操作 Kudu 表的语法参考。
|
||||
|
||||
## 数据类型
|
||||
|
||||
| 类型 | 说明 | 示例 |
|
||||
|------|------|------|
|
||||
| BOOLEAN | 布尔 | active BOOLEAN |
|
||||
| TINYINT | 1字节整数 | level TINYINT |
|
||||
| SMALLINT | 2字节整数 | age SMALLINT |
|
||||
| INT | 4字节整数 | count INT |
|
||||
| BIGINT | 8字节整数 | id BIGINT |
|
||||
| FLOAT | 4字节浮点 | score FLOAT |
|
||||
| DOUBLE | 8字节浮点 | price DOUBLE |
|
||||
| DECIMAL(p,s) | 定点数 | amount DECIMAL(18,2) |
|
||||
| STRING | 变长字符串 | name STRING |
|
||||
| VARCHAR(n) | 变长字符串(限长) | code VARCHAR(50) |
|
||||
| CHAR(n) | 定长字符串 | flag CHAR(1) |
|
||||
| TIMESTAMP | 时间戳(微秒精度) | created_at TIMESTAMP |
|
||||
| DATE | 日期 | birth_date DATE |
|
||||
| BINARY | 二进制 | data BINARY |
|
||||
|
||||
**注意**:Kudu 不支持 ARRAY、MAP、STRUCT 等复杂类型。
|
||||
|
||||
---
|
||||
|
||||
## 时间函数
|
||||
|
||||
```sql
|
||||
-- 当前时间
|
||||
NOW() -- 当前日期时间
|
||||
CURRENT_TIMESTAMP() -- 当前时间戳
|
||||
UNIX_TIMESTAMP() -- 当前 Unix 时间戳(秒)
|
||||
TO_DATE(NOW()) -- 当前日期
|
||||
|
||||
-- 格式转换
|
||||
FROM_UNIXTIME(timestamp, 'yyyy-MM-dd') -- Unix 时间戳转格式化字符串
|
||||
FROM_UNIXTIME(timestamp, 'yyyy-MM-dd HH:mm:ss')
|
||||
CAST(string_col AS TIMESTAMP) -- 字符串转时间戳
|
||||
CAST(timestamp_col AS STRING) -- 时间戳转字符串
|
||||
|
||||
-- 日期计算
|
||||
DAYS_ADD(date_col, 7) -- 加7天
|
||||
DAYS_SUB(date_col, 7) -- 减7天
|
||||
ADD_MONTHS(date_col, 3) -- 加3个月(Impala 6.0+)
|
||||
DATE_ADD(date_col, INTERVAL 7 DAY) -- 加7天(标准语法)
|
||||
DATEDIFF(end_date, start_date) -- 日期差(天数)
|
||||
MONTHS_BETWEEN(date1, date2) -- 月份差
|
||||
|
||||
-- 日期提取
|
||||
YEAR(date_col) -- 年
|
||||
MONTH(date_col) -- 月
|
||||
DAY(date_col) -- 日
|
||||
DAYOFWEEK(date_col) -- 周几 (1=周日)
|
||||
DAYOFYEAR(date_col) -- 年中第几天
|
||||
HOUR(timestamp_col) -- 时
|
||||
MINUTE(timestamp_col) -- 分
|
||||
SECOND(timestamp_col) -- 秒
|
||||
QUARTER(date_col) -- 季度 (1-4)
|
||||
WEEKOFYEAR(date_col) -- 年中第几周
|
||||
|
||||
-- Impala 日期格式符
|
||||
-- yyyy: 4位年, MM: 2位月, dd: 2位日
|
||||
-- HH: 24小时制, mm: 分钟, ss: 秒
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## 字符串函数
|
||||
|
||||
```sql
|
||||
-- 常用函数
|
||||
CONCAT(str1, str2) -- 字符串拼接(仅2个参数)
|
||||
CONCAT_WS('-', str1, str2, ...) -- 用分隔符拼接
|
||||
LOWER(str) -- 转小写
|
||||
UPPER(str) -- 转大写
|
||||
TRIM(str) -- 去两端空格
|
||||
LTRIM(str) -- 去左空格
|
||||
RTRIM(str) -- 去右空格
|
||||
LENGTH(str) -- 字符串长度
|
||||
SUBSTR(str, pos, len) -- 截取字符串(pos从1开始)
|
||||
SUBSTRING(str, pos, len) -- 同上
|
||||
LEFT(str, len) -- 取左边len个字符
|
||||
RIGHT(str, len) -- 取右边len个字符
|
||||
REVERSE(str) -- 反转字符串
|
||||
REPEAT(str, n) -- 重复n次
|
||||
SPACE(n) -- 生成n个空格
|
||||
|
||||
-- 查找与替换
|
||||
INSTR(str, substr) -- 查找子串位置
|
||||
LOCATE(substr, str, pos) -- 从pos位置查找
|
||||
REPLACE(str, old, new) -- 替换
|
||||
REGEXP_EXTRACT(str, pattern, idx) -- 正则提取
|
||||
REGEXP_REPLACE(str, pattern, replacement) -- 正则替换
|
||||
|
||||
-- 分割
|
||||
SPLIT_PART(str, delimiter, idx) -- 取分割后第idx部分
|
||||
|
||||
-- 其他
|
||||
INITCAP(str) -- 首字母大写
|
||||
LPAD(str, len, pad) -- 左填充
|
||||
RPAD(str, len, pad) -- 右填充
|
||||
HEX(col) -- 转16进制
|
||||
UNHEX(str) -- 16进制转字符串
|
||||
```
|
||||
|
||||
**注意**:Impala 的 `CONCAT` 只接受 2 个参数,多参数拼接用 `CONCAT_WS`。
|
||||
|
||||
---
|
||||
|
||||
## 聚合函数
|
||||
|
||||
```sql
|
||||
-- 基础聚合
|
||||
COUNT(*) -- 计数(含NULL行)
|
||||
COUNT(col) -- 计数(不含NULL)
|
||||
COUNT(DISTINCT col) -- 去重计数
|
||||
SUM(col) -- 求和
|
||||
AVG(col) -- 平均值
|
||||
MIN(col) -- 最小值
|
||||
MAX(col) -- 最大值
|
||||
|
||||
-- 集合聚合
|
||||
GROUP_CONCAT(col SEPARATOR ',') -- 字符串聚合
|
||||
|
||||
-- 统计函数
|
||||
VARIANCE(col) -- 方差
|
||||
VAR_POP(col) -- 总体方差
|
||||
VAR_SAMP(col) -- 样本方差
|
||||
STDDEV(col) -- 标准差
|
||||
STDDEV_POP(col) -- 总体标准差
|
||||
STDDEV_SAMP(col) -- 样本标准差
|
||||
|
||||
-- 近似函数
|
||||
NDV(col) -- 近似去重计数(Impala 特有,比 COUNT(DISTINCT) 快)
|
||||
APPROX_COUNT_DISTINCT(col) -- 近似去重计数
|
||||
|
||||
-- 其他
|
||||
FIRST_VALUE(col) -- 窗口内第一个值
|
||||
LAST_VALUE(col) -- 窗口内最后一个值
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## 条件表达式
|
||||
|
||||
```sql
|
||||
-- CASE WHEN
|
||||
CASE
|
||||
WHEN condition1 THEN result1
|
||||
WHEN condition2 THEN result2
|
||||
ELSE default_result
|
||||
END
|
||||
|
||||
-- CASE 字段匹配
|
||||
CASE field
|
||||
WHEN value1 THEN result1
|
||||
WHEN value2 THEN result2
|
||||
ELSE default_result
|
||||
END
|
||||
|
||||
-- COALESCE(取第一个非空值)
|
||||
COALESCE(col1, col2, default_value)
|
||||
|
||||
-- NULLIF(相等返回NULL)
|
||||
NULLIF(col1, col2)
|
||||
|
||||
-- IF(简单条件)
|
||||
IF(condition, true_value, false_value)
|
||||
|
||||
-- ISNULL / ISNOTNULL
|
||||
ISNULL(col) -- 判断是否为NULL
|
||||
ISNOTNULL(col) -- 判断是否不为NULL
|
||||
|
||||
-- NVL(空值替换)
|
||||
NVL(col, default_value)
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## Kudu 特有操作
|
||||
|
||||
### INSERT INTO
|
||||
|
||||
```sql
|
||||
-- 追加写入
|
||||
INSERT INTO kudu_table VALUES (1, 'test', 100.00);
|
||||
INSERT INTO kudu_table SELECT * FROM other_table WHERE ...;
|
||||
```
|
||||
|
||||
### UPSERT INTO(Kudu 核心能力)
|
||||
|
||||
```sql
|
||||
-- 主键存在则更新,不存在则插入
|
||||
UPSERT INTO kudu_table VALUES (1, 'test', 100.00);
|
||||
UPSERT INTO kudu_table SELECT * FROM staging_table WHERE ...;
|
||||
```
|
||||
|
||||
### UPDATE
|
||||
|
||||
```sql
|
||||
-- 更新数据(主键列不可更新)
|
||||
UPDATE kudu_table SET status = 'active' WHERE id = 1;
|
||||
UPDATE kudu_table SET amount = amount * 1.1 WHERE date < '2026-01-01';
|
||||
```
|
||||
|
||||
### DELETE
|
||||
|
||||
```sql
|
||||
-- 删除数据
|
||||
DELETE FROM kudu_table WHERE id = 1;
|
||||
DELETE FROM kudu_table WHERE date < '2026-01-01';
|
||||
```
|
||||
|
||||
### ALTER TABLE(Kudu 特有)
|
||||
|
||||
```sql
|
||||
-- 添加列
|
||||
ALTER TABLE kudu_table ADD COLUMNS (new_col STRING COMMENT '新列');
|
||||
|
||||
-- 删除列
|
||||
ALTER TABLE kudu_table DROP COLUMN old_col;
|
||||
|
||||
-- 修改列类型
|
||||
ALTER TABLE kudu_table CHANGE old_name new_name STRING;
|
||||
|
||||
-- 添加范围分区
|
||||
ALTER TABLE kudu_table ADD RANGE PARTITION
|
||||
'2026-06-01' <= VALUES < '2026-07-01';
|
||||
|
||||
-- 删除范围分区
|
||||
ALTER TABLE kudu_table DROP RANGE PARTITION
|
||||
'2026-01-01' <= VALUES < '2026-02-01';
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## 分区操作
|
||||
|
||||
```sql
|
||||
-- Hash 分区(建表时指定)
|
||||
PARTITION BY HASH(id) PARTITIONS 8
|
||||
|
||||
-- Range 分区(建表时指定)
|
||||
PARTITION BY RANGE(stat_date) (
|
||||
PARTITION '2026-01-01' <= VALUES < '2026-02-01',
|
||||
PARTITION '2026-02-01' <= VALUES < '2026-03-01'
|
||||
)
|
||||
|
||||
-- Hash + Range 组合
|
||||
PARTITION BY
|
||||
HASH(id) PARTITIONS 4,
|
||||
RANGE(stat_date) (...)
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## 与 Spark SQL / Hive 的主要差异
|
||||
|
||||
| 特性 | Spark SQL | Hive | Kudu (Impala) | 说明 |
|
||||
|------|-----------|------|--------------|------|
|
||||
| **INSERT OVERWRITE** | ✅ | ✅ | ❌ | Kudu 不支持,用 DELETE + INSERT 替代 |
|
||||
| **UPSERT** | ❌ | ❌ | ✅ | Kudu 独有核心能力 |
|
||||
| **UPDATE** | ❌ | 仅ACID表 | ✅ | Kudu 原生支持 |
|
||||
| **DELETE** | ❌ | 仅ACID表 | ✅ | Kudu 原生支持 |
|
||||
| **主键约束** | ❌ 无约束 | ❌ 无约束 | ✅ 强制主键 | Kudu 表必须有主键 |
|
||||
| **复杂类型** | ✅ ARRAY/MAP/STRUCT | ✅ 完整支持 | ❌ 不支持 | Kudu 限制 |
|
||||
| **CONCAT 多参数** | ✅ 任意个数 | ✅ 任意个数 | ❌ 仅2个参数 | Impala 用 CONCAT_WS |
|
||||
| **近似去重** | `approx_count_distinct` | `approx_count_distinct` | `NDV` | Impala 特有函数名 |
|
||||
| **临时表链式处理** | ✅ 推荐 | ✅ 推荐 | ❌ 不需要 | Kudu 用 UPSERT 单步 |
|
||||
| **CTE (WITH)** | ✅ 支持 | ✅ 支持 | ✅ 支持 | 都支持 |
|
||||
| **MERGE INTO** | ✅ 支持 | ❌ | ❌ | 用 UPSERT 替代 |
|
||||
| **分区类型** | 目录分区 | 目录分区 | Hash/Range 内置 | Kudu 分区机制不同 |
|
||||
| **分桶** | 可选 | 可选 | Hash 分区替代 | 概念类似但实现不同 |
|
||||
| **日期格式** | `yyyy-MM-dd` | `yyyy-MM-dd` | `yyyy-MM-dd` | 格式一致 |
|
||||
| **collect_list/set** | ✅ | ✅ | ❌ | Impala 用 GROUP_CONCAT |
|
||||
| **ALTER ADD COLUMN** | ✅ | ✅ | ✅ | Kudu 支持在线加列 |
|
||||
| **ALTER DROP COLUMN** | 部分支持 | ✅ | ✅ | Kudu 支持在线删列 |
|
||||
|
||||
---
|
||||
|
||||
## SQL 生成规则
|
||||
|
||||
### 通用规则(所有引擎统一)
|
||||
|
||||
1. **禁止使用 CTE (WITH 子句)**,每个主要逻辑步骤必须物化为临时表
|
||||
2. **先 DROP 再 CREATE**:`DROP TABLE IF EXISTS ...; CREATE TABLE ... AS SELECT ...;`
|
||||
3. **禁止 `SELECT *`**,必须明确列出所有字段
|
||||
4. 多表查询时所有表必须使用简短别名
|
||||
5. 每个步骤前添加注释说明
|
||||
6. **谓词下推**:过滤条件前置,JOIN 时在 WHERE 中一并添加过滤
|
||||
7. 临时表命名:`${db_tmp_env}.tmp_{业务简称}_{步骤序号}`
|
||||
|
||||
### Kudu 特有规则
|
||||
|
||||
1. **Kudu 表不支持 `INSERT OVERWRITE`**,用 `DELETE + INSERT` 或 `UPSERT` 替代
|
||||
2. **最后一步优先使用 `UPSERT INTO`**(Kudu 核心优势:主键存在则更新,不存在则插入)
|
||||
3. 需要全量刷新时:先 `DELETE FROM` 再 `INSERT INTO`
|
||||
4. 支持 `UPDATE` 和 `DELETE`(Kudu 表独有)
|
||||
5. Kudu 表必须有 `PRIMARY KEY`,主键列不能为 NULL
|
||||
6. `CONCAT` 只接受 2 个参数,多参数用 `CONCAT_WS`
|
||||
7. 不支持 `collect_list` / `collect_set`,用 `GROUP_CONCAT` 替代
|
||||
8. 近似去重用 `NDV()` 函数
|
||||
9. 时间范围筛选:
|
||||
```sql
|
||||
-- 日账期过滤
|
||||
WHERE stat_date = '${day_id}'
|
||||
-- 日期范围
|
||||
WHERE stat_date >= DAYS_SUB(TO_DATE('${day_id}'), 30)
|
||||
AND stat_date < '${day_id}'
|
||||
```
|
||||
|
||||
### SQL 脚本结构
|
||||
|
||||
```sql
|
||||
-- =====================================================================
|
||||
-- @SqlName: kudu-D-SQL-{表名}
|
||||
-- @Engine: kudu
|
||||
-- ...(头注释)
|
||||
-- =====================================================================
|
||||
|
||||
-- Step01: {步骤描述}
|
||||
DROP TABLE IF EXISTS ${db_tmp_env}.tmp_xxx_01;
|
||||
CREATE TABLE ${db_tmp_env}.tmp_xxx_01 AS
|
||||
SELECT ...;
|
||||
|
||||
-- Step02: {步骤描述}
|
||||
DROP TABLE IF EXISTS ${db_tmp_env}.tmp_xxx_02;
|
||||
CREATE TABLE ${db_tmp_env}.tmp_xxx_02 AS
|
||||
SELECT ...;
|
||||
|
||||
-- 最后一步:UPSERT 写入 Kudu 目标表
|
||||
UPSERT INTO ${db_eda_env}.target_table
|
||||
SELECT ...;
|
||||
```
|
||||
@@ -0,0 +1,414 @@
|
||||
# Spark SQL 语法要点
|
||||
|
||||
## 数据类型
|
||||
|
||||
| 类型 | 说明 | 示例 |
|
||||
|------|------|------|
|
||||
| STRING | 字符串 | name STRING |
|
||||
| INT | 整数 | age INT |
|
||||
| BIGINT | 大整数 | id BIGINT |
|
||||
| DOUBLE | 浮点数 | price DOUBLE |
|
||||
| DECIMAL(p,s) | 定点数 | amount DECIMAL(18,2) |
|
||||
| BOOLEAN | 布尔 | active BOOLEAN |
|
||||
| DATE | 日期 | birth_date DATE |
|
||||
| TIMESTAMP | 时间戳 | created_at TIMESTAMP |
|
||||
| ARRAY<type> | 数组 | tags ARRAY<STRING> |
|
||||
| MAP<key,value> | 映射 | props MAP<STRING,STRING> |
|
||||
| STRUCT<field:type,...> | 结构体 | user STRUCT<id:INT,name:STRING> |
|
||||
|
||||
---
|
||||
|
||||
## 时间函数
|
||||
|
||||
```sql
|
||||
-- 当前时间
|
||||
current_date()
|
||||
current_timestamp()
|
||||
now()
|
||||
|
||||
-- 格式转换
|
||||
date_format(date_col, 'yyyy-MM-dd')
|
||||
date_format(timestamp_col, 'yyyy-MM-dd HH:mm:ss')
|
||||
to_date(string_col, 'yyyy-MM-dd')
|
||||
to_timestamp(string_col, 'yyyy-MM-dd HH:mm:ss')
|
||||
|
||||
-- 日期计算
|
||||
date_add(date_col, 7) -- 加7天
|
||||
date_sub(date_col, 7) -- 减7天
|
||||
add_months(date_col, 3) -- 加3个月
|
||||
datediff(end_date, start_date) -- 日期差(天数)
|
||||
|
||||
-- 日期提取
|
||||
year(date_col)
|
||||
month(date_col)
|
||||
day(date_col)
|
||||
dayofweek(date_col)
|
||||
hour(timestamp_col)
|
||||
minute(timestamp_col)
|
||||
second(timestamp_col)
|
||||
|
||||
-- 季度、周
|
||||
quarter(date_col) -- 季度 (1-4)
|
||||
weekofyear(date_col) -- 年中第几周
|
||||
|
||||
-- Unix 时间戳
|
||||
unix_timestamp(date_col) -- 转 Unix 时间戳
|
||||
from_unixtime(timestamp) -- Unix 时间戳转时间字符串
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## 字符串函数
|
||||
|
||||
```sql
|
||||
-- 常用函数
|
||||
concat(str1, str2, ...) -- 字符串拼接
|
||||
concat_ws('-', str1, str2, ...) -- 用分隔符拼接
|
||||
lower(str) -- 转小写
|
||||
upper(str) -- 转大写
|
||||
trim(str) -- 去两端空格
|
||||
ltrim(str) -- 去左空格
|
||||
rtrim(str) -- 去右空格
|
||||
length(str) -- 字符串长度
|
||||
substring(str, pos, len) -- 截取字符串
|
||||
left(str, len) -- 取左边len个字符
|
||||
right(str, len) -- 取右边len个字符
|
||||
reverse(str) -- 反转字符串
|
||||
repeat(str, n) -- 重复n次
|
||||
space(n) -- 生成n个空格
|
||||
|
||||
-- 查找与替换
|
||||
instr(str, substr) -- 查找子串位置
|
||||
locate(substr, str, pos) -- 从pos位置查找
|
||||
replace(str, old, new) -- 替换
|
||||
regexp_extract(str, pattern, idx) -- 正则提取
|
||||
regexp_replace(str, pattern, replacement) -- 正则替换
|
||||
|
||||
-- 分割
|
||||
split(str, delimiter) -- 分割成数组
|
||||
split_part(str, delimiter, idx) -- 取分割后的第idx部分
|
||||
|
||||
-- 其他
|
||||
initcap(str) -- 首字母大写
|
||||
lpad(str, len, pad) -- 左填充
|
||||
rpad(str, len, pad) -- 右填充
|
||||
levenshtein(str1, str2) -- 编辑距离
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## 条件表达式
|
||||
|
||||
```sql
|
||||
-- CASE WHEN
|
||||
CASE
|
||||
WHEN condition1 THEN result1
|
||||
WHEN condition2 THEN result2
|
||||
ELSE default_result
|
||||
END
|
||||
|
||||
-- CASE 字段匹配
|
||||
CASE field
|
||||
WHEN value1 THEN result1
|
||||
WHEN value2 THEN result2
|
||||
ELSE default_result
|
||||
END
|
||||
|
||||
-- COALESCE(取第一个非空值)
|
||||
COALESCE(col1, col2, default_value)
|
||||
|
||||
-- NULLIF(相等返回NULL)
|
||||
NULLIF(col1, col2)
|
||||
|
||||
-- IF(简单条件)
|
||||
IF(condition, true_value, false_value)
|
||||
|
||||
-- NVL(空值替换)
|
||||
NVL(col, default_value)
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## 聚合函数
|
||||
|
||||
```sql
|
||||
-- 基础聚合
|
||||
COUNT(*) -- 计数(含NULL行)
|
||||
COUNT(col) -- 计数(不含NULL)
|
||||
COUNT(DISTINCT col) -- 去重计数
|
||||
SUM(col) -- 求和
|
||||
AVG(col) -- 平均值
|
||||
MIN(col) -- 最小值
|
||||
MAX(col) -- 最大值
|
||||
|
||||
-- 集合聚合
|
||||
collect_list(col) -- 返回数组(不去重)
|
||||
collect_set(col) -- 返回数组(去重)
|
||||
|
||||
-- 统计函数
|
||||
variance(col) -- 方差
|
||||
var_pop(col) -- 总体方差
|
||||
var_samp(col) -- 样本方差
|
||||
stddev(col) -- 标准差
|
||||
stddev_pop(col) -- 总体标准差
|
||||
stddev_samp(col) -- 样本标准差
|
||||
|
||||
-- 近似函数
|
||||
approx_count_distinct(col) -- 近似去重计数(大数据量优化)
|
||||
|
||||
-- 其他
|
||||
first(col) -- 第一个值
|
||||
last(col) -- 最后一个值
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## 数学函数
|
||||
|
||||
```sql
|
||||
-- 基础运算
|
||||
abs(col) -- 绝对值
|
||||
round(col, digits) -- 四舍五入
|
||||
ceil(col) -- 向上取整
|
||||
floor(col) -- 向下取整
|
||||
sign(col) -- 符号 (-1, 0, 1)
|
||||
|
||||
-- 指数与对数
|
||||
exp(col) -- e的指数
|
||||
log(col) -- 自然对数
|
||||
log10(col) -- 10为底对数
|
||||
log2(col) -- 2为底对数
|
||||
pow(col, n) -- 幂运算
|
||||
sqrt(col) -- 平方根
|
||||
|
||||
-- 三角函数
|
||||
sin(col), cos(col), tan(col)
|
||||
asin(col), acos(col), atan(col)
|
||||
|
||||
-- 随机数
|
||||
rand() -- 随机数 (0-1)
|
||||
rand(seed) -- 指定种子随机数
|
||||
|
||||
-- 其他
|
||||
cbrt(col) -- 立方根
|
||||
hex(col) -- 转16进制
|
||||
unhex(col) -- 16进制转字符串
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## 数组函数
|
||||
|
||||
```sql
|
||||
-- 创建数组
|
||||
array(val1, val2, ...) -- 创建数组
|
||||
|
||||
-- 访问
|
||||
array_contains(arr, val) -- 判断是否包含
|
||||
element_at(arr, idx) -- 取元素(idx从1开始)
|
||||
arr[idx] -- 取元素(idx从0开始)
|
||||
|
||||
-- 操作
|
||||
size(arr) -- 数组长度
|
||||
array_join(arr, delimiter) -- 数组转字符串
|
||||
concat(arr1, arr2) -- 数组拼接
|
||||
|
||||
-- 展开
|
||||
explode(arr) -- 展开数组为多行
|
||||
posexplode(arr) -- 展开数组(带位置索引)
|
||||
|
||||
-- 排序与去重
|
||||
sort_array(arr) -- 排序
|
||||
array_distinct(arr) -- 去重
|
||||
array_remove(arr, val) -- 移除元素
|
||||
array_union(arr1, arr2) -- 并集
|
||||
array_intersect(arr1, arr2) -- 交集
|
||||
array_except(arr1, arr2) -- 差集
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## Map 函数
|
||||
|
||||
```sql
|
||||
-- 创建 Map
|
||||
map(key1, val1, key2, val2, ...) -- 创建 Map
|
||||
str_to_map(str, delim1, delim2) -- 字符串转 Map
|
||||
|
||||
-- 访问
|
||||
map_contains(map, key) -- 判断是否包含key
|
||||
element_at(map, key) -- 取值
|
||||
map[key] -- 取值
|
||||
map_keys(map) -- 取所有key(返回数组)
|
||||
map_values(map) -- 取所有value(返回数组)
|
||||
|
||||
-- 操作
|
||||
size(map) -- Map大小
|
||||
map_concat(map1, map2) -- Map合并
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## JSON 函数
|
||||
|
||||
```sql
|
||||
-- 解析
|
||||
get_json_object(json_str, path) -- 提取JSON字段
|
||||
json_tuple(json_str, field1, ...) -- 提取多个字段
|
||||
|
||||
-- 转换
|
||||
from_json(json_str, schema) -- JSON转结构体
|
||||
to_json(struct_col) -- 结构体转JSON
|
||||
|
||||
-- Schema 定义示例
|
||||
from_json('{"name":"张三","age":25}', 'name STRING, age INT')
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## 分区表操作
|
||||
|
||||
```sql
|
||||
-- 创建分区表
|
||||
CREATE TABLE target_table (
|
||||
id BIGINT,
|
||||
name STRING,
|
||||
amount DECIMAL(18,2)
|
||||
)
|
||||
PARTITIONED BY (day_id STRING)
|
||||
STORED AS PARQUET;
|
||||
|
||||
-- 写入指定分区
|
||||
INSERT OVERWRITE TABLE target_table
|
||||
PARTITION (day_id = '${day_id}')
|
||||
SELECT id, name, amount
|
||||
FROM source_table
|
||||
WHERE ...
|
||||
|
||||
-- 动态分区写入
|
||||
INSERT OVERWRITE TABLE target_table
|
||||
PARTITION (day_id)
|
||||
SELECT id, name, amount, day_id
|
||||
FROM source_table;
|
||||
|
||||
-- 查看分区
|
||||
SHOW PARTITIONS target_table;
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## 临时表与视图
|
||||
|
||||
```sql
|
||||
-- 创建临时表
|
||||
CREATE TEMPORARY TABLE tmp_table AS
|
||||
SELECT ...
|
||||
|
||||
-- 创建临时视图
|
||||
CREATE TEMPORARY VIEW tmp_view AS
|
||||
SELECT ...
|
||||
|
||||
-- 全局临时视图(跨Session)
|
||||
CREATE GLOBAL TEMPORARY VIEW global_view AS
|
||||
SELECT ...
|
||||
|
||||
-- 删除
|
||||
DROP TABLE IF EXISTS tmp_table;
|
||||
DROP VIEW IF EXISTS tmp_view;
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## MERGE INTO(更新插入)
|
||||
|
||||
```sql
|
||||
-- MERGE INTO 语法
|
||||
MERGE INTO target_table t
|
||||
USING source_table s
|
||||
ON t.id = s.id
|
||||
WHEN MATCHED THEN UPDATE SET t.name = s.name, t.amount = s.amount
|
||||
WHEN NOT MATCHED THEN INSERT (id, name, amount) VALUES (s.id, s.name, s.amount)
|
||||
|
||||
-- 仅更新
|
||||
MERGE INTO target_table t
|
||||
USING source_table s
|
||||
ON t.id = s.id
|
||||
WHEN MATCHED THEN UPDATE SET *
|
||||
|
||||
-- 仅插入
|
||||
MERGE INTO target_table t
|
||||
USING source_table s
|
||||
ON t.id = s.id
|
||||
WHEN NOT MATCHED THEN INSERT *
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## Spark SQL 不支持的特性
|
||||
|
||||
| PostgreSQL 特性 | Spark SQL | 替代方案 |
|
||||
|------------------|-----------|----------|
|
||||
| CREATE INDEX | ❌ 不支持 | 依赖存储格式优化(Parquet/ORC) |
|
||||
| CREATE TRIGGER | ❌ 不支持 | 使用程序逻辑处理 |
|
||||
| FOREIGN KEY 约束 | ❌ 不强制 | 数据关联靠 JOIN 保证 |
|
||||
| CHECK 约束 | ❌ 不支持 | 使用过滤条件 |
|
||||
| ON CONFLICT (UPSERT) | 使用 MERGE INTO | - |
|
||||
| WITH RECURSIVE | Spark 3.x+ 支持 | 或用程序迭代 |
|
||||
| 物化视图 | ❌ 不支持 | 使用缓存或临时表 |
|
||||
| 存储过程 | ❌ 不支持 | 使用外部程序 |
|
||||
| FOR UPDATE 锁 | ❌ 不支持 | 无行级锁概念 |
|
||||
|
||||
---
|
||||
|
||||
## SQL 生成规则
|
||||
|
||||
### 通用规则(所有引擎统一)
|
||||
|
||||
1. **禁止使用 CTE (WITH 子句)**,每个主要逻辑步骤必须物化为临时表
|
||||
2. **先 DROP 再 CREATE**:`DROP TABLE IF EXISTS ...; CREATE TABLE ... AS SELECT ...;`
|
||||
3. **禁止 `SELECT *`**,必须明确列出所有字段
|
||||
4. 多表查询时所有表必须使用简短别名
|
||||
5. 每个步骤前添加注释说明
|
||||
6. **谓词下推**:过滤条件前置,JOIN 时在 WHERE 中一并添加过滤
|
||||
7. 临时表命名:`${db_tmp_env}.tmp_{业务简称}_{步骤序号}`
|
||||
8. 目标表命名:`${db_eda_env}.{目标表名}`
|
||||
|
||||
### Spark 特有规则
|
||||
|
||||
1. 使用 `INSERT OVERWRITE TABLE` 写入目标表
|
||||
2. 分区表必须指定分区:`PARTITION (day_id = '${day_id}')`
|
||||
3. 最后一步写入目标表,中间步骤物化临时表
|
||||
4. 日期函数:`date_format()`, `to_date()`, `date_add()`, `add_months()`
|
||||
5. 时间范围筛选:
|
||||
```sql
|
||||
-- 日账期过滤
|
||||
WHERE day_id = '${day_id}'
|
||||
-- 最近N个月(月份格式 yyyyMM)
|
||||
WHERE month_id >= date_format(add_months(to_date('${month_id}', 'yyyyMM'), -N), 'yyyyMM')
|
||||
AND month_id < '${month_id}'
|
||||
```
|
||||
|
||||
### SQL 脚本结构
|
||||
|
||||
```sql
|
||||
-- =====================================================================
|
||||
-- @SqlName: spark-D-SQL-{表名}
|
||||
-- @Engine: spark
|
||||
-- ...(头注释)
|
||||
-- =====================================================================
|
||||
|
||||
-- Step01: {步骤描述}
|
||||
DROP TABLE IF EXISTS ${db_tmp_env}.tmp_xxx_01;
|
||||
CREATE TABLE ${db_tmp_env}.tmp_xxx_01 AS
|
||||
SELECT ...;
|
||||
|
||||
-- Step02: {步骤描述}
|
||||
DROP TABLE IF EXISTS ${db_tmp_env}.tmp_xxx_02;
|
||||
CREATE TABLE ${db_tmp_env}.tmp_xxx_02 AS
|
||||
SELECT ...;
|
||||
|
||||
-- 最后一步:写入目标表
|
||||
INSERT OVERWRITE TABLE ${db_eda_env}.target_table
|
||||
PARTITION (day_id = '${day_id}')
|
||||
SELECT ...;
|
||||
```
|
||||
@@ -0,0 +1,306 @@
|
||||
# 窗口函数速查
|
||||
|
||||
## 基本语法
|
||||
|
||||
```sql
|
||||
函数名() OVER (
|
||||
PARTITION BY 分组字段 -- 可选:分组
|
||||
ORDER BY 排序字段 -- 可选:排序
|
||||
ROWS/RANGE 窗口范围 -- 可选:窗口范围
|
||||
)
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## 排序函数
|
||||
|
||||
| 函数 | 说明 | 特点 | 适用场景 |
|
||||
|------|------|------|----------|
|
||||
| ROW_NUMBER() | 连续排名 | 不跳号,相同值不同排名 | 每组取前N条、去重 |
|
||||
| RANK() | 排名 | 跳号,相同值相同排名 | 成绩排名 |
|
||||
| DENSE_RANK() | 紧密排名 | 不跳号,相同值相同排名 | 连续名次 |
|
||||
| NTILE(n) | 分桶 | 分成n组 | 数据分片、抽样 |
|
||||
|
||||
### ROW_NUMBER 示例
|
||||
|
||||
```sql
|
||||
-- 每个部门薪资最高的员工(取第一名)
|
||||
SELECT *
|
||||
FROM (
|
||||
SELECT
|
||||
name,
|
||||
department,
|
||||
salary,
|
||||
ROW_NUMBER() OVER (PARTITION BY department ORDER BY salary DESC) AS rn
|
||||
FROM employees
|
||||
) t
|
||||
WHERE rn = 1
|
||||
|
||||
-- 去重:每个用户取最新订单
|
||||
SELECT *
|
||||
FROM (
|
||||
SELECT
|
||||
*,
|
||||
ROW_NUMBER() OVER (PARTITION BY user_id ORDER BY created_at DESC) AS rn
|
||||
FROM orders
|
||||
) t
|
||||
WHERE rn = 1
|
||||
```
|
||||
|
||||
### RANK 与 DENSE_RANK 示例
|
||||
|
||||
```sql
|
||||
-- 成绩排名(跳号)
|
||||
SELECT
|
||||
name,
|
||||
score,
|
||||
RANK() OVER (ORDER BY score DESC) AS rank, -- 1,2,2,4,5...
|
||||
DENSE_RANK() OVER (ORDER BY score DESC) AS dense -- 1,2,2,3,4...
|
||||
FROM students
|
||||
```
|
||||
|
||||
### NTILE 示例
|
||||
|
||||
```sql
|
||||
-- 将用户分成4组(业绩分位)
|
||||
SELECT
|
||||
name,
|
||||
sales,
|
||||
NTILE(4) OVER (ORDER BY sales DESC) AS quartile -- 1(最高)到4(最低)
|
||||
FROM sales_data
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## 聚合函数(窗口内)
|
||||
|
||||
| 函数 | 说明 |
|
||||
|------|------|
|
||||
| SUM(col) OVER | 累计求和 |
|
||||
| AVG(col) OVER | 累计平均 |
|
||||
| COUNT(col) OVER | 窗口内计数 |
|
||||
| MAX(col) OVER | 窗口内最大值 |
|
||||
| MIN(col) OVER | 窗口内最小值 |
|
||||
|
||||
### 累计求和示例
|
||||
|
||||
```sql
|
||||
-- 累计销售额(从开始到当前)
|
||||
SELECT
|
||||
date,
|
||||
amount,
|
||||
SUM(amount) OVER (ORDER BY date) AS cumulative_amount
|
||||
FROM daily_sales
|
||||
|
||||
-- 分组累计(每个部门累计)
|
||||
SELECT
|
||||
date,
|
||||
department,
|
||||
amount,
|
||||
SUM(amount) OVER (PARTITION BY department ORDER BY date) AS dept_cumulative
|
||||
FROM sales_data
|
||||
```
|
||||
|
||||
### 移动平均示例
|
||||
|
||||
```sql
|
||||
-- 7天移动平均
|
||||
SELECT
|
||||
date,
|
||||
amount,
|
||||
AVG(amount) OVER (
|
||||
ORDER BY date
|
||||
ROWS BETWEEN 6 PRECEDING AND CURRENT ROW
|
||||
) AS moving_avg_7d
|
||||
FROM daily_sales
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## 偏移函数
|
||||
|
||||
| 函数 | 说明 | 适用场景 |
|
||||
|------|------|----------|
|
||||
| LAG(col, n) | 取前n行的值 | 环比、查看历史值 |
|
||||
| LAG(col, n, default) | 取前n行,无值返回default | 防止NULL |
|
||||
| LEAD(col, n) | 取后n行的值 | 查看未来值 |
|
||||
| LEAD(col, n, default) | 取后n行,无值返回default | 防止NULL |
|
||||
| FIRST_VALUE(col) | 窗口第一个值 | 组内首个值 |
|
||||
| LAST_VALUE(col) | 窗口最后一个值 | 组内末尾值 |
|
||||
|
||||
### LAG 示例(环比计算)
|
||||
|
||||
```sql
|
||||
-- 日环比增长
|
||||
SELECT
|
||||
date,
|
||||
amount,
|
||||
LAG(amount, 1) OVER (ORDER BY date) AS prev_day,
|
||||
amount - LAG(amount, 1) OVER (ORDER BY date) AS daily_growth,
|
||||
ROUND((amount - LAG(amount, 1) OVER (ORDER BY date))
|
||||
/ LAG(amount, 1) OVER (ORDER BY date) * 100, 2) AS growth_rate_pct
|
||||
FROM daily_sales
|
||||
|
||||
-- 月度同比(取去年同期)
|
||||
SELECT
|
||||
month,
|
||||
revenue,
|
||||
LAG(revenue, 12) OVER (ORDER BY month) AS prev_year_revenue,
|
||||
ROUND((revenue - LAG(revenue, 12) OVER (ORDER BY month))
|
||||
/ LAG(revenue, 12) OVER (ORDER BY month) * 100, 2) AS yoy_growth_pct
|
||||
FROM monthly_revenue
|
||||
```
|
||||
|
||||
### LEAD 示例
|
||||
|
||||
```sql
|
||||
-- 查看下一行数据
|
||||
SELECT
|
||||
date,
|
||||
amount,
|
||||
LEAD(amount, 1) OVER (ORDER BY date) AS next_day_amount
|
||||
FROM daily_sales
|
||||
```
|
||||
|
||||
### FIRST_VALUE / LAST_VALUE 示例
|
||||
|
||||
```sql
|
||||
-- 每个部门薪资最高和最低的人
|
||||
SELECT
|
||||
name,
|
||||
department,
|
||||
salary,
|
||||
FIRST_VALUE(name) OVER (PARTITION BY department ORDER BY salary DESC) AS highest_paid,
|
||||
LAST_VALUE(name) OVER (
|
||||
PARTITION BY department
|
||||
ORDER BY salary DESC
|
||||
ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING
|
||||
) AS lowest_paid
|
||||
FROM employees
|
||||
```
|
||||
|
||||
**注意**:LAST_VALUE 默认窗口是 `ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW`,需要显式指定全窗口才能取到最后值。
|
||||
|
||||
---
|
||||
|
||||
## 窗口范围定义
|
||||
|
||||
### ROWS(基于行数)
|
||||
|
||||
```sql
|
||||
ROWS BETWEEN 3 PRECEDING AND CURRENT ROW -- 前3行到当前行
|
||||
ROWS BETWEEN 6 PRECEDING AND 1 FOLLOWING -- 前6行到后1行
|
||||
ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW -- 从开始到当前
|
||||
ROWS BETWEEN CURRENT ROW AND 3 FOLLOWING -- 当前行到后3行
|
||||
ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING -- 全窗口
|
||||
ROWS BETWEEN 1 PRECEDING AND 1 FOLLOWING -- 当前行及前后各1行(共3行)
|
||||
```
|
||||
|
||||
### RANGE(基于值范围)
|
||||
|
||||
```sql
|
||||
RANGE BETWEEN 100 PRECEDING AND CURRENT ROW -- 值差100以内
|
||||
RANGE BETWEEN INTERVAL '7' DAY PRECEDING AND CURRENT ROW -- 7天内
|
||||
```
|
||||
|
||||
**ROWS vs RANGE**:
|
||||
- ROWS:固定行数,不受值影响
|
||||
- RANGE:根据排序字段的值计算范围
|
||||
|
||||
---
|
||||
|
||||
## 实战案例
|
||||
|
||||
### 案例1:分组取Top N
|
||||
|
||||
```sql
|
||||
-- 每个部门薪资前3名
|
||||
SELECT *
|
||||
FROM (
|
||||
SELECT
|
||||
name,
|
||||
department,
|
||||
salary,
|
||||
ROW_NUMBER() OVER (PARTITION BY department ORDER BY salary DESC) AS rn
|
||||
FROM employees
|
||||
) t
|
||||
WHERE rn <= 3
|
||||
```
|
||||
|
||||
### 案例2:连续问题判断
|
||||
|
||||
```sql
|
||||
-- 判断是否连续增长(连续3天增长)
|
||||
SELECT
|
||||
date,
|
||||
amount,
|
||||
CASE
|
||||
WHEN amount > LAG(amount, 1) OVER (ORDER BY date)
|
||||
AND LAG(amount, 1) OVER (ORDER BY date) > LAG(amount, 2) OVER (ORDER BY date)
|
||||
THEN '连续增长'
|
||||
ELSE '非连续增长'
|
||||
END AS trend
|
||||
FROM daily_sales
|
||||
```
|
||||
|
||||
### 案例3:组内占比
|
||||
|
||||
```sql
|
||||
-- 每个部门各员工薪资占比
|
||||
SELECT
|
||||
name,
|
||||
department,
|
||||
salary,
|
||||
ROUND(salary / SUM(salary) OVER (PARTITION BY department) * 100, 2) AS salary_pct
|
||||
FROM employees
|
||||
```
|
||||
|
||||
### 案例4:累计百分比(帕累托分析)
|
||||
|
||||
```sql
|
||||
-- 80/20分析:哪些客户贡献了80%销售额
|
||||
SELECT
|
||||
customer_id,
|
||||
sales_amount,
|
||||
ROUND(SUM(sales_amount) OVER (ORDER BY sales_amount DESC)
|
||||
/ SUM(sales_amount) OVER () * 100, 2) AS cumulative_pct
|
||||
FROM customer_sales
|
||||
ORDER BY sales_amount DESC
|
||||
```
|
||||
|
||||
### 案例5:缺失值填充
|
||||
|
||||
```sql
|
||||
-- 用前一个有效值填充NULL
|
||||
SELECT
|
||||
date,
|
||||
amount,
|
||||
LAST_VALUE(amount IGNORE NULLS) OVER (ORDER BY date) AS filled_amount
|
||||
FROM sales_data
|
||||
```
|
||||
|
||||
---
|
||||
|
||||
## 性能优化建议
|
||||
|
||||
1. **减少 PARTITION BY 分组数量**:分组越多,计算越慢
|
||||
2. **合理使用窗口范围**:避免全窗口扫描
|
||||
3. **先过滤再窗口**:WHERE 条件前置,减少数据量
|
||||
4. **避免嵌套窗口函数**:多次调用会重复计算
|
||||
|
||||
```sql
|
||||
-- 推荐:先过滤
|
||||
SELECT
|
||||
*,
|
||||
ROW_NUMBER() OVER (PARTITION BY dept ORDER BY salary DESC) AS rn
|
||||
FROM employees
|
||||
WHERE hire_date >= '2024-01-01' -- 先过滤,减少数据量
|
||||
|
||||
-- 不推荐:先窗口再过滤(窗口函数在全部数据上执行)
|
||||
SELECT *
|
||||
FROM (
|
||||
SELECT *, ROW_NUMBER() OVER (...) AS rn
|
||||
FROM employees
|
||||
) t
|
||||
WHERE hire_date >= '2024-01-01'
|
||||
```
|
||||
Reference in New Issue
Block a user