Mysql常用函数的汇总,可看下面文章
https://cloud.tencent.com/developer/article/1641021
返回两个指定的日期之间相差的天数
DATEDIFF(expr1,expr2)
SELECT DATEDIFF('2007-12-31 23:59:59','2007-12-30'); # 1 SELECT DATEDIFF('2010-11-30 23:59:59','2010-12-31'); # 31