sql -- 示例1: 直接用DATEDIFF函数计算两个日期之间的天数差 SELECT DATEDIFF AS days;

-- 示例2: 用变量来存储日期值，并计算天数差 SET @date1 = '2021-07-15'; SET @date2 = '2021-07-13'; SELECT DATEDIFF AS days;