为什么SQL Server DATETIME类型节省了每秒1/300的时间？ [英] Why SQL Server DATETIME type saves time in ticks of 1/300 of a sec?

问题描述

SQLServer datetime格式存储为8个字节，其中前四个字节是自1900年1月1日以来的天数，其他四个字节是自午夜以来的刻度数。而这个刻度是秒的1/300。

SQLServer datetime format is stored as 8 bytes where the first four bytes are number of days since Jan 1, 1900 and the other four bytes are number of ticks since midnight. And the tick is 1/300 of the second.

我想知道为什么会这样？那个1/300来自哪里？必须有一些历史原因。

I'm wondering why is that? Where is that 1/300 came from? There must be some historic reason for that.

推荐答案

是的，有一个历史原因：UNIX！

Yes, there is a historical reason: UNIX !

有关详细信息，请阅读杰出的文章由Joe Celko。

For details, read this excelent article by Joe Celko.

以下是您要查找的详细信息：

Here is the detail you're looking for:

T-SQL
中的时间数据曾经是UNIX系统时钟滴答的囚犯，只能在$ 4 $ b到三进制小数的四舍五入错误。新的ANSI / ISO数据
类型可以转到七个十进制小时，具有真实的DATE和TIME数据
类型。由于它们是新的，大多数程序员尚未使用它们。

Temporal data in T-SQL used to be a prisoner of UNIX system clock ticks and could only go to three decimal seconds with rounding errors. The new ANSI/ISO data types can go to seven decimal seconds, have a true DATE and TIME data types. Since they are new, most programmers are not using them yet.

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