SELECT * FROM products WHERE price BETWEEN 10 AND 50

SELECT * FROM products WHERE price >= 10 AND price <= 50

SELECT * FROM products WHERE price IN (10, 50)

SELECT * FROM products WHERE price > 10 AND price < 50

DATE_ADD('2023-12-31', INTERVAL 1 DAY) 返回 2024-01-01

DATE_ADD('2023-05-15 10:00:00', INTERVAL 3 HOUR) 返回 2023-05-15 13:00:00

DATE_ADD('2023-01-31', INTERVAL 1 MONTH) 返回 2023-02-28

DATE_ADD('2023-02-28', INTERVAL 1 YEAR) 返回 2024-02-29

select a, min(b) from table group by a, c不会报错

select a, b, c from table group by a, b, c, d不会报错

select a, b, c from table group by a, c不会报错

select a, b, c from table group by a, c, d不会报错

可用于生成序列组合（如日期与产品）

与INNER JOIN不加条件效果相同

返回两表的笛卡尔积

必须配合ON条件使用

DENSE_RANK() OVER (PARTITION BY MONTH(sale_date) ORDER BY sale_amount DESC)

ROW_NUMBER() OVER (PARTITION BY employee_id, MONTH(sale_date) ORDER BY sale_amount DESC)

DENSE_RANK() OVER (PARTITION BY employee_id, MONTH(sale_date) ORDER BY sale_amount DESC)

RANK() OVER (PARTITION BY employee_id, MONTH(sale_date) ORDER BY sale_amount DESC)

以上都可以，但A最简单直接

HAVING COUNT(DISTINCT order_id) >= 2

HAVING COUNT(user_id) >= 2

HAVING COUNT(order_id) >= 2