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T-SQL Performance Tip: NOT IN vs NOT EXISTS

T-SQL Performance Tip: NOT IN vs NOT EXISTS

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Avoid using NOT IN whilst comparing nullable columns. Use NOT EXISTS instead.

When NOT IN is used in a query, SQL Server compares each result to null (even if no rows are returned). NOT EXISTS does not perform a comparison with nulls.

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Charlie Frank

Charlie has over a decade of experience in website administration and technology management. As the site admin, he oversees all technical aspects of running a high-traffic online platform, ensuring optimal performance, security, and user experience.
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