How can I convert bigint (UNIX timestamp) to datet

Question

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

Answer 1

Like this

add the Unix (epoch) datetime to the base date in seconds

this will get it for now (2010-05-25 07:56:23.000)

 SELECT dateadd(s,1274756183,'19700101 05:00:00:000')

If you want to go reverse, take a look at this http://wiki.lessthandot.com/index.php/Epoch_Date

Answer 2

//BIGINT UNIX TIMESTAMP CONVERSION upto Millisecond Accuracy
CREATE FUNCTION [dbo].[ConvertUnixTimestamp] (@Datetime [BIGINT]) RETURNS DATETIME
AS
BEGIN

    RETURN DATEADD(MILLISECOND, cast(@Datetime as bigint) % 1000, 
    DATEADD(SECOND, (cast(@Datetime as bigint) / 1000)%60, 
    DATEADD(MINUTE, ((cast(@Datetime as bigint) / 1000)/60)%60, 
    DATEADD(HOUR, ((cast(@Datetime as bigint) / 1000)/60)/60, '19700101'))))
END

Answer 3

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

Answer 4

Adding n seconds to 1970-01-01 will give you a UTC date because n, the Unix timestamp, is the number of seconds that have elapsed since 00:00:00 Coordinated Universal Time (UTC), Thursday, 1 January 1970.

In SQL Server 2016, you can convert one time zone to another using AT TIME ZONE. You just need to know the name of the time zone in Windows standard format:

SELECT *
FROM (VALUES (1514808000), (1527854400)) AS Tests(UnixTimestamp)
CROSS APPLY (SELECT DATEADD(SECOND, UnixTimestamp, '1970-01-01') AT TIME ZONE 'UTC') AS CA1(UTCDate)
CROSS APPLY (SELECT UTCDate AT TIME ZONE 'Pacific Standard Time') AS CA2(LocalDate)

| UnixTimestamp | UTCDate                    | LocalDate                  |
|---------------|----------------------------|----------------------------|
| 1514808000    | 2018-01-01 12:00:00 +00:00 | 2018-01-01 04:00:00 -08:00 |
| 1527854400    | 2018-06-01 12:00:00 +00:00 | 2018-06-01 05:00:00 -07:00 |

Or simply:

SELECT *, DATEADD(SECOND, UnixTimestamp, '1970-01-01') AT TIME ZONE 'UTC' AT TIME ZONE 'Pacific Standard Time'
FROM (VALUES (1514808000), (1527854400)) AS Tests(UnixTimestamp)

| UnixTimestamp | LocalDate                  |
|---------------|----------------------------|
| 1514808000    | 2018-01-01 04:00:00 -08:00 |
| 1527854400    | 2018-06-01 05:00:00 -07:00 |

Notes:

• You can chop off the timezone information by casting DATETIMEOFFSET to DATETIME.
• The conversion takes daylight savings time into account. Pacific time was UTC-08:00 on January 2018 and UTC-07:00 on Jun 2018.