datediff()函数在 SQL 中是一个用于计算两个日期之间差值,返回两个日期之间的差,整数
datediff(datepart, startdate, enddate)
datepart:year, quarter, month, dayofyear, day, week, hour, minute, second, millisecond, microsecond, nanosecond
startdate:开始时间
enddate:结束时间
select datediff(year,vac36,vac37) from vac1 -- 年差值
select datediff(quarter,vac36,vac37) from vac1 -- 季度差值
select datediff(month,vac36,vac37) from vac1 --月差值
select datediff(day,vac36,vac37) from vac1 --天数差值
select datediff(week,vac36,vac37) from vac1 --周数差值
select datediff(weekday,vac36,vac37) from vac1 --工作日差值
select datediff(hour,vac36,vac37) from vac1 --小时
select datediff(minute,vac36,vac37) from vac1 --分
select datediff(second,vac36,vac37) from vac1 --秒
select datediff(millisecond,vac36,vac37) from vac1 --毫秒
select datediff(microsecond,vac36,vac37) from vac1 --微秒
select datediff(nanosecond,vac36,vac37) from vac1 --毫微秒
select datediff(DAYOFYEAR,vac36,vac37) from vac1 --年份中的天数(不太明白)