T-SQL Variable vs String Equivalent

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T-SQL Variable vs String Equivalent

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ChrisM@Work SSC Guru Points: 186127 More actions · Answer 1

If you examine the two plans in the first post of this thread, the first one – for the query with a constant predicate – has been considered for simple parameterization (WHERE [field_value]=@1). Simple parameterization promotes plan re-use – you probably want two separate plans cached for WHERE [field_value] = 'Yes' and WHERE [field_value] = 'No' unless the distribution stats were wildly different. There’s a good chance that SQL Server will use the same plan for both queries.

^{“Write the query the simplest way. If through testing it becomes clear that the performance is inadequate, consider alternative query forms.” - Gail Shaw}

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