Defensive database programming: eliminating IF statements.

The following pattern is quite common in database programming: IF EXISTS(some query) BEGIN DO SOMETHING; END When such code runs in high concurrency situations, it may not work as expected. I will provide a repro when such logic fails 40% of the time. The following script provides a test table and attempts to implement optimistic locking using rowversion columns: CREATE TABLE dbo . TwoINTs ( ID INT NOT NULL, i1 INT NOT NULL, i2 INT NOT NULL, version ROWVERSION ) GO SET NOCOUNT ON ; DECLARE @i INT...(read more)

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