Why Does My SQL WHERE Clause Seem to Ignore a Parameter?

Troubleshooting SQL WHERE Clauses: Addressing Parameter Overlook

This article addresses a common SQL query issue where the WHERE clause seemingly ignores a specified parameter. Consider this example:

<code class="language-sql">SELECT * FROM people 
WHERE
university='2' 
AND MATCH (lname,fname) AGAINST ('+massive' IN BOOLEAN MODE) 
OR (fname LIKE '%box%' OR lname LIKE '%box%') </code>

This query, unexpectedly, returns rows where university is not '2'. The problem lies in operator precedence and the order of operations.

The solution involves restructuring the WHERE clause using parentheses to correctly group the conditions:

<code class="language-sql">SELECT * FROM people 
WHERE
    university='2' 
    AND (MATCH (lname,fname) AGAINST ('+massive' IN BOOLEAN MODE) 
         OR fname LIKE '%box%' 
         OR lname LIKE '%box%')</code>

By enclosing the MATCH and LIKE conditions within parentheses, we ensure that both the full-text search and the LIKE conditions are applied only to rows where university = '2'. The AND operator then correctly restricts the results to those meeting all specified criteria. This revised structure guarantees accurate results based on the intended parameter filtering.

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