Remove References to AT TIME ZONE in FOR SYSTEM_TIME AS OF

[LarnuUK]

The documentation states that AT TIME ZONE can be used in conjunction with FOR SYSTEM_TIME AS FOR. The example gives, however, gives an error:

Incorrect syntax near 'AT'.

This is true if you use the clause against a VIEW or a TABLE, the same error occurs. db<>fiddle

It appears, therefore, that the documentation is incorrect, and the section should be removed, which this PR does.

If wanted, however, I am happy to add an example that uses a variable of datetimeoffset with AT TIME ZONE used against it, but I would want to check out how this works before doing so, to make sure the documentation is informative.

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[Court72]

@rwestMSFT

Can you review the proposed changes?

When the changes are ready for publication, add a #sign-off comment to signal that the PR is ready for the review team to merge.

#label:"aq-pr-triaged"
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[rwestMSFT]

Hi @LarnuUK

I originally authorized the PR last year that added this change, and didn't do due diligence to test it properly beforehand.

On the WideWorldImporters database, you can do this:

DECLARE @CustomerTimeZone NVARCHAR(128) = 'Central European Standard Time';

SELECT StockItemID, ValidFrom,
    --Assign the known offset only
    ValidFrom AT TIME ZONE 'Pacific Standard Time' AS OrderDate_TimeZonePST,
    --Assign the known offset, then convert to another time zone
    ValidFrom AT TIME ZONE @CustomerTimeZone AS OrderDate_TimeZoneCustomer
FROM Warehouse.StockItems;

However, you are correct, and AT TIME ZONE is not compatible with AS OF.

Instead of approving your PR directly, which removes the example entirely, I'm going to roll back the change from last year, but you will still get contributor credit.

Thanks for your contribution.

[LarnuUK]

Thanks @rwestMSFT . I'll close this PR then as well, as a roll back does solve the problem as well.

[rwestMSFT]

@LarnuUK Thanks - I'll comment here once I've refreshed all the articles in this area, because some of them haven't been looked at in a while.