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WHERE clauses should not contain redundant conditions

Description

    The "WHERE clauses should not contain redundant conditions" code rule states that WHERE clauses should not contain conditions that are unnecessary or redundant. This means that the WHERE clause should only contain conditions that are necessary for the query to return the desired results. Redundant conditions can lead to inefficient query execution as the engine will need to process them unnecessarily. Furthermore, redundant conditions can lead to incorrect query results if the conditions are not logically equivalent. It is therefore important to ensure that the WHERE clause contains only the necessary conditions.

Key Benefits

  • Reduced complexity: WHERE clauses should not contain redundant conditions to avoid unnecessary complexity in the query.
  • Improved performance: By avoiding redundant conditions, the query can be optimized and executed more efficiently.
  • Increased accuracy: Redundant conditions can lead to incorrect results, so avoiding them helps ensure accuracy.

 

Non-compliant Code Example

SELECT Product.ProductID,  
Product.Name,
Color  
FROM Production.Product  
WHERE ListPrice > 50  AND ListPrice = 200;  --Non compliant code (Where clause is having redundant conditions)

Compliant Code Example

SELECT Product.ProductID,  
Product.Name,
Color  
FROM Production.Product  
WHERE ListPrice > 50;  --Compliant code (Where clause is not having redundant conditions)
Visual Expert 2024
 VETSQLRULE67