将 SQL 中的 BigInt 值转换为 c# 中的日期时间

Question

I usually use the SQL function below to convert bigint in sql to datetime in SQL Server 2005.

DECLARE @datetime AS bigint, @day AS int, @ms AS int
SET @datetime = 129471410567460000 
SET @ms = (@datetime / CAST(10000 AS bigint)) % 86400000
SET @day = @datetime / CAST(864000000000 AS bigint) - 109207
SELECT DATEADD(ms,@ms, DATEADD(day, @day, 0))

How do i do it using c#? I am able to read in time value (129471410567460000) from the SQL server and want to convert to datetime. The datetime will be used in a c# application.

Cheers

Answer 1

Are you trying to convert a bigint in SQL Server to a datetime in C# ? If so, you would do something like:

var tickValue = 129471410567460000;
var datetime = new DateTime( tickValue );

If however, you are tying to convert a bigint value in SQL Server to a datetime value in SQL Server then look at the following link:

Convert .NET Ticks to SQL Server DateTime

If you are trying mimic your exact logic (how you are getting that tick value is its own mystery):

var tickValue = 129471410567460000;
var ms = ( tickValue / 10000 ) % 86400000;
var day = tickValue / 864000000000 - 109207;

var startDate = new DateTime( 1900, 1, 1 );
var resultDateTime = startDate.AddMilliseconds( ms ).AddDays( day );

The trick to this logic is the start date. In SQL Server, day zero = '1900-01-01' even though DateTime values can store values going back to 1753.

---

In comments, you mentioned that the SQL method was posted in a forum. It is crucial that you know the method used to calculate the bigint value. The forum seems to suggest that this value is a Win32 FILETIME structure: that stores the date as 100-nanosecond intervals since 1601 . If that is the case, the code you would use in C# is:

var startDate = new DateTime( 1601, 1, 1 );
var resultDateTime = startDate.AddTicks( tickValue );

You will note that this value returns 2003-05-14 4:51:56 PM which is the approximate date and time of the forum thread.

Answer 2

Solution is

DateTime.FromFileTimeUtc()

Answer 3

public DateTime ConvertLongFormate2DateTime(long iDatelongValue)
{
    try
    {
        var iSecondCal = (iDatelongValue / 1000 + 8 * 60 * 60);
        var startDate = new DateTime(1970, 01, 01);
        DateTime resultDateTime = startDate.AddSeconds(iSecondCal);
        return resultDateTime;
    }
    catch (Exception)
    {
        throw;
    }
}

Answer 4

You could make it a stored procedure, then call that from C#.

Answer 5

Try this:

long datetime = 129471410567460000;
int ms = (int)((datetime / 10000) % 86400000);
int day = (int)(datetime / 864000000000L) - 109207;


DateTime dt = DateTime.MinValue.AddDays(day).AddMilliseconds(ms);