由网友(无敌软妹噼里啪啦)分享简介：我想从传入请求数据库存储值进行比较时间戳。当然，SQL Server保留的时间毫秒的一些precision，当读入一个.NET日期时间，它包括那些毫秒。到达请求到该系统，但是，没有提供的precision，所以我需要简单地丢弃毫秒。I'm trying to compare a time stamp from an...

我想从传入请求数据库存储值进行比较时间戳。当然，SQL Server保留的时间毫秒的一些precision，当读入一个.NET日期时间，它包括那些毫秒。到达请求到该系统，但是，没有提供的precision，所以我需要简单地丢弃毫秒。

I'm trying to compare a time stamp from an incoming request to a database stored value. SQL Server of course keeps some precision of milliseconds on the time, and when read into a .NET DateTime, it includes those milliseconds. The incoming request to the system, however, does not offer that precision, so I need to simply drop the milliseconds.

我觉得我失去了一些东西很明显，但我还没有找到一种优雅的方式来做到这一点（C＃）。

I feel like I'm missing something obvious, but I haven't found an elegant way to do it (C#).

推荐答案

下面的工作的日期时间，有小数毫秒，也preserves Kind属性（本地，UTC或undefined）。

The following will work for a DateTime that has fractional milliseconds, and also preserves the Kind property (Local, Utc or Undefined).

DateTime dateTime = ... anything ...
dateTime = new DateTime(
    dateTime.Ticks - (dateTime.Ticks % TimeSpan.TicksPerSecond), 
    dateTime.Kind
    );

或同等及更短的：

or the equivalent and shorter:

dateTime = dateTime.AddTicks( - (dateTime.Ticks % TimeSpan.TicksPerSecond));

这可以概括为一个扩展方法：

This could be generalized into an extension method:

public static DateTime Truncate(this DateTime dateTime, TimeSpan timeSpan)
{
    if (timeSpan == TimeSpan.Zero) return dateTime; // Or could throw an ArgumentException
    return dateTime.AddTicks(-(dateTime.Ticks % timeSpan.Ticks));
}

它用于如下：

which is used as follows:

dateTime = dateTime.Truncate(TimeSpan.FromMilliseconds(1)); // Truncate to whole ms
dateTime = dateTime.Truncate(TimeSpan.FromSeconds(1)); // Truncate to whole second
dateTime = dateTime.Truncate(TimeSpan.FromMinutes(1)); // Truncate to whole minute
...