sql - datediff 奇怪的东西 - SQL Server

Question

测试：

    select datediff(week, '20190104 23:01:11.821', '20190105 23:01:11.821')
    select datediff(week, '20190104 23:01:11.821', '20190106 23:01:11.821')
    select datediff(week, '20190104 23:01:11.821', '20190107 23:01:11.821')
    select datediff(week, '20190104 23:01:11.821', '20190108 23:01:11.821')
    select datediff(week, '20190104 23:01:11.821', '20190109 23:01:11.821')
    select datediff(week, '20190104 23:01:11.821', '20190113 23:01:11.821')

这返回

    0
    1
    1
    1
    2

我只在第一个返回值中看到常识。到底是怎么回事？例如，为什么最后一个返回 2 周？！其他人怎么回报他们回报的？

标签： sqlsql-server

Answer 1

Datediff 计算跨越边界的频率。

SELECT DATEPART(WEEK, '20190104 23:01:11.821')
,       DATEPART(WEEK, '20190106 23:01:11.821')

退货

1   2

所以越过了一周的边界，所以 datediff 返回 1。