Yet another use of OUTER APPLY in defensive programming
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by Alexander Kuznetsov
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Published on Wed, 06 Jun 2012 21:58:00 GMT
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2012/06/06
22:45 UTC
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Defensive Programming
|Transact SQL
When a SELECT is used to populate variables from a subquery, it fails to change them if the subquery returns nothing - and that can lead to subtle bugs. We shall use OUTER APPLY to eliminate this problem. Prerequisites All we need is the following mock function that imitates a subquery: CREATE FUNCTION dbo.BoxById ( @BoxId INT ) RETURNS TABLE AS RETURN ( SELECT CAST ( 1 AS INT ) AS [Length] , CAST ( 2 AS INT ) AS [Width] , CAST ( 3 AS INT ) AS [Height] WHERE @BoxId = 1 ) ; Let us assume that this...(read more)
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