以毫秒为单位的日期时间表示？

我有一个 SQL 服务器时间戳，需要将其转换为以毫秒为单位的时间表示。我可以用普通 SQL 做到这一点吗？如果没有，我已经将它提取到 C # 中的 DateTime变量中。有没有可能得到一个毫秒表示呢？

谢谢,
Teja.

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In C#, you can write

(long)(date - new DateTime(1970, 1, 1)).TotalMilliseconds
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SELECT CAST(DATEDIFF(S, '1970-01-01', SYSDATETIME()) AS BIGINT) * 1000

This does not give you full precision, but DATEDIFF(MS... causes overflow. If seconds are good enough, this should do it.

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最佳答案

You're probably trying to convert to a UNIX-like timestamp, which are in UTC:

yourDateTime.ToUniversalTime().Subtract(
new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc)
).TotalMilliseconds

This also avoids summertime issues, since UTC doesn't have those.

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This other solution for covert datetime to unixtimestampmillis C#.

private static readonly DateTime UnixEpoch = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);


public static long GetCurrentUnixTimestampMillis()
{
DateTime localDateTime, univDateTime;
localDateTime = DateTime.Now;
univDateTime = localDateTime.ToUniversalTime();
return (long)(univDateTime - UnixEpoch).TotalMilliseconds;
}
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Using the answer of Andoma, this is what I'm doing

You can create a Struct or a Class like this one

struct Date
{
public static double GetTime(DateTime dateTime)
{
return dateTime.ToUniversalTime().Subtract(new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc)).TotalMilliseconds;
}


public static DateTime DateTimeParse(double milliseconds)
{
return new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc).AddMilliseconds(milliseconds).ToLocalTime();
}


}

And you can use this in your code as following

DateTime dateTime = DateTime.Now;


double total = Date.GetTime(dateTime);


dateTime = Date.DateTimeParse(total);

I hope this help you

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As of .NET 4.6, you can use a DateTimeOffset object to get the unix milliseconds. It has a constructor which takes a DateTime object, so you can just pass in your object as demonstrated below.

DateTime yourDateTime;
long yourDateTimeMilliseconds = new DateTimeOffset(yourDateTime).ToUnixTimeMilliseconds();

As noted in other answers, make sure yourDateTime has the correct Kind specified, or use .ToUniversalTime() to convert it to UTC time first.

Here you can learn more about DateTimeOffset.

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There are ToUnixTime() and ToUnixTimeMs() methods in DateTimeExtensions class

DateTime.UtcNow.ToUnixTimeMs()


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