July 22, 2019

Tip: T-SQL Performance–NOT IN vs NOT EXISTS

July 22, 2019 2:07 pm

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. ? Visit the DevX Tip Bank ?

T-SQL Performance Tip: NOT IN vs NOT EXISTS

July 22, 2019 1:07 pm

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.