SA0034 : Use parentheses to improve readability and avoid mistakes because of logical operator precedence

Use parentheses to improve readability and avoid mistakes because of logical operator precedence

When more than one logical operator is used in a statement, NOT is evaluated first, then AND, and finally OR. The Arithmetic (and bitwise) operators are handled before logical operators.

The use of parentheses, even when not required, can improve the readability of queries and reduce the chance of making a subtle mistake because of operator precedence. There is no significant performance penalty in using parentheses.

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

Rule has no parameters.

The rule does not need Analysis Context or SQL Connection.

Design Rules, Code Smells

There is no additional info for this rule.

 1-- OR clause used without parenthesis
 2SELECT     title_id ,
 3           type ,
 4           price
 5FROM       pubs.dbo.titles
 6WHERE      type = 'physics'
 7        OR type = 'architecture'
 8       AND advance > 30
 9
10SELECT     title_id ,
11           type ,
12           price
13FROM       pubs.dbo.titles
14WHERE      type = 'physics'
15        OR ( type = 'architecture'
16             AND price > 30 )
17
18SELECT     title_id ,
19           type ,
20           price
21FROM       titles
22WHERE      ( type = 'physics'
23              OR type = 'architecture' )
24       AND advance > 30

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