SRP0013.md

SQL Server Rule: SRP0013

Assembly	SqlServer.Rules.dll
Namespace	SqlServer.Rules.Performance
Class	AvoidOuterJoinsRule

Rule Information

Id	SRP0013
Friendly Name	Existence tested with JOIN
Category	Performance
Ignorable	true
Applicable Types	Procedure
	Scalar Function
	Table Valued Function
	View

Description

Consider replacing the OUTER JOIN with EXISTS.

Summary

Consider replacing the OUTER JOIN with EXISTS

Examples

SHOULD FLAG AS PROBLEM:

    SELECT a.*
    FROM a
    LEFT JOIN b ON a.id = b.id
    WHERE b.id IS NULL 

SHOULD NOT FLAG AS PROBLEM:

    SELECT a.*, b.*
    FROM a
    LEFT JOIN b ON a.id = b.id
    WHERE b.id IS NULL  

    SELECT a.*, b.*
    FROM a
    LEFT JOIN b ON a.id = b.id