SQL 服务器 - 将 EST 显示为 PST？

Question

Server is in NY and date column (DateTime) is being filled as EST. How do users in California view this DateTime as the local PST?

I tried:

declare @dte DateTime = '20190919 10:01:01'
select @dte EST, @dte At Time Zone 'Pacific Standard Time' As PST

And I get

EST

2019-09-19 10:01:01.000 

PST

2019-09-19 10:01:01.000 -07:00

I am looking for 2019-09-19 07:01:01.000 -07:00

Answer 1

Jeroen already said this in his comment, but I'm making the code concrete so you can see what he means.

Take your initial date, that you know the time zone for, but SQL Server doesn't yet, and tell it the time zone explicitly:

DECLARE @dte datetime = '20190919 10:01:01';
SELECT
  @dte AT TIME ZONE 'Eastern Standard Time';

That returns a DATETIMEOFFSET value:

2019-09-19 10:01:01.000 -04:00

Next, convert that value to Pacific time by wrapping it in another AT TIME ZONE :

DECLARE @dte datetime = '20190919 10:01:01';
SELECT
  (@dte AT TIME ZONE 'Eastern Standard Time') AT TIME ZONE 'Pacific Standard Time' AS datetime;

That returns another DATETIMEOFFSET :

2019-09-19 07:01:01.000 -07:00

Last but not least, for your presentation purposes, wrap that in a CAST so that you only get a DATETIME for your end users:

DECLARE @dte datetime = '20190919 10:01:01';
SELECT
  CAST((@dte AT TIME ZONE 'Eastern Standard Time') AT TIME ZONE 'Pacific Standard Time' AS datetime);

Results:

2019-09-19 07:01:01.000

And Bob's your uncle.

Of course, if you want to take the lazy approach, DATEADD will get you where you want to be, too:

DECLARE @dte datetime = '20190919 10:01:01';
SELECT
  DATEADD(HOUR, -3, @dte);

2019-09-19 07:01:01.000