SA0176 : Consider merging nested IF statements to improve readability

When writing T-SQL in SQL Server, using multiple nested IF statements without ELSE clauses can make your code harder to read and maintain. Merging these nested statements into a single IF can improve readability and clarity.

For example:

1-- Example of problematic nested IF statements
2IF (condition1)
3BEGIN
4    IF (condition2)
5    BEGIN
6        ... -- Some action
7    END
8END

This pattern can confuse developers and make future enhancements or troubleshooting more challenging. Instead, combining the conditions into a single IF statement can make the logic clearer.

1-- Improved version
2IF (condition1 AND condition2)
3BEGIN
4    ... -- Some action
5END

• Reduces code complexity by minimizing nesting.

• Improves maintainability by making the logical flow clearer.

Merging nested IF statements into a single statement improves code readability and maintainability in SQL Server.

Follow these steps to address the issue:

1. Identify nested IF statements without ELSE clauses in your T-SQL code.

2. Combine the conditions of the nested IF statements into a single IF statement using the AND logical operator.

3. Use the combined condition to execute the necessary SQL statements within a single BEGIN…END block.

For example:

 1-- Example of problematic nested IF statements
 2IF (condition1)
 3BEGIN
 4    IF (condition2)
 5    BEGIN
 6        -- Some action
 7    END
 8END
 9
10-- Improved version
11IF (condition1 AND condition2)
12BEGIN
13    -- Some action
14END

The rule has a Batch scope and is applied only on the SQL script.

Rule has no parameters.

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Design Rules, Code Smells

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