如何在 SQL Server 中获得完整的毫秒数？答案

【问题标题】：How can I get the full milliseconds in SQL server?如何在 SQL Server 中获得完整的毫秒数？
【发布时间】：2018-01-29 11:52:06
【问题描述】：

DECLARE @Now DATETIME2(7) = SYSDATETIME();

SELECT
    [Datetime2(1)] = DATEPART(MILLISECOND,CAST(@Now AS DATETIME2(1))),
    [Datetime2(2)] = DATEPART(MILLISECOND,CAST(@Now AS DATETIME2(2))),
    [Datetime2(3)] = DATEPART(MILLISECOND,CAST(@Now AS DATETIME2(3))),
    [Datetime2(4)] = DATEPART(MILLISECOND,CAST(@Now AS DATETIME2(4))),
    [Datetime2(5)] = DATEPART(MILLISECOND,CAST(@Now AS DATETIME2(5))),
    [Datetime2(6)] = DATEPART(MILLISECOND,CAST(@Now AS DATETIME2(6))),
    [Datetime2(7)] = DATEPART(MILLISECOND,CAST(@Now AS DATETIME2(7)))

执行返回以下示例值：

300 260 265 264 264 264 264

如何获得更高的精度？

【问题讨论】：

标签： sql-server datepart datetime2

【解决方案1】：

没关系，函数返回一个 int，这不是我所期望的。我应该使用 NANOSECOND，然后划分它。

DECLARE @Now DATETIME2(7) = SYSDATETIME();

SELECT
    [Datetime2(1)] = DATEPART(NANOSECOND,CAST(@Now AS DATETIME2(1)))/1000000.0,
    [Datetime2(2)] = DATEPART(NANOSECOND,CAST(@Now AS DATETIME2(2)))/1000000.0,
    [Datetime2(3)] = DATEPART(NANOSECOND,CAST(@Now AS DATETIME2(3)))/1000000.0,
    [Datetime2(4)] = DATEPART(NANOSECOND,CAST(@Now AS DATETIME2(4)))/1000000.0,
    [Datetime2(5)] = DATEPART(NANOSECOND,CAST(@Now AS DATETIME2(5)))/1000000.0,
    [Datetime2(6)] = DATEPART(NANOSECOND,CAST(@Now AS DATETIME2(6)))/1000000.0,
    [Datetime2(7)] = DATEPART(NANOSECOND,CAST(@Now AS DATETIME2(7)))/1000000.0

【讨论】：