How can I convert bigint (UNIX timestamp) to datetime in SQL Server?

This worked for me:

Select    dateadd(S, [unixtime], '1970-01-01')From [Table]

In case any one wonders why 1970-01-01, This is called Epoch time.

Below is a quote from Wikipedia:

The number of seconds that have elapsed since 00:00:00 Coordinated Universal Time (UTC), Thursday, 1 January 1970,[1][note 1] not counting leap seconds.

try:

CREATE FUNCTION dbo.fn_ConvertToDateTime (@Datetime BIGINT)RETURNS DATETIMEASBEGIN    DECLARE @LocalTimeOffset BIGINT           ,@AdjustedLocalDatetime BIGINT;    SET @LocalTimeOffset = DATEDIFF(second,GETDATE(),GETUTCDATE())    SET @AdjustedLocalDatetime = @Datetime - @LocalTimeOffset    RETURN (SELECT DATEADD(second,@AdjustedLocalDatetime, CAST('1970-01-01 00:00:00' AS datetime)))END;GO

If anyone getting below error:

Arithmetic overflow error converting expression to data type int

due to unix timestamp is in bigint (instead of int), you can use this:

SELECT DATEADD(S, CONVERT(int,LEFT(1462924862735870900, 10)), '1970-01-01')FROM TABLE

Replace the hardcoded timestamp for your actual column with unix-timestamp

Source: MSSQL bigint Unix Timestamp to Datetime with milliseconds