Why Does My PHP Script Throw a 'mysql_fetch_array(): supplied argument is not a valid MySQL result' Warning?

Invalid Argument in mysql_fetch_array()

Problem Description

Upon executing a PHP script, the following error is encountered:

Warning: mysql_fetch_array(): supplied argument is not a valid MySQL result [duplicate]

Origin of the Error

This error is typically caused when the $result variable, which is expected to contain a valid MySQL result set, is actually empty or invalid.

Code Snippet

The code snippet causing the issue:

$connector = new DbConnector();
$result = $connector->query('SELECT title,content FROM staff_vacancies ORDER BY ordering LIMIT 0,100');
while ($row = $connector->fetchArray($result)){

echo $row['title'].'</h3>';
echo $row['content'];
}

Possible Causes

Here are possible causes for the invalid $result variable:

• Query Failure: The query executed using $connector->query() returned an empty result set or failed due to an error.
• Syntax Error: The database query itself may contain syntax errors, causing it to fail.

Solution

To resolve this issue, consider the following steps:

• Check for Query Errors: Use mysql_error() to check for errors in the query executed by $connector->query(). If an error occurred, it will be displayed.
• Review the Query: Inspect the database query for any syntax or logical errors that may cause it to fail.
• Enhanced Query Method: Refactor the query() method in DbConnector.php to handle error catching and provide a more descriptive error message.

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