Archive for T-SQL

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T-SQL Race Conditions (and how to avoid them)

I’ve been writing T-SQL stored procedures for many years now, and I never fully understood how the concurrency of multiple users truly affects the asynchronous operation of certain types of paradigms until now. Take the following T-SQL: SELECT @ID = ID FROM tblTable WHERE nvhSomeText = ‘match’ IF @ID IS NULL INSERT INTO tblTable (nvhSomeText, [...]

DECLARE CURSOR … FOR UPDATE

Just a quick post to basically document somewhere the problem I was getting and the solution I found.Take the following cursor declaration: DECLARE cur_Columns CURSOR LOCAL FOR SELECT DISTINCT person_id FROM Company_People WHERE company_id = @company_id FOR UPDATE OF person_id There is no obvious reason to me why this should not work, but attempting to [...]