What potential pitfalls could lead to the error message "Warning: mysql_fetch_array(): supplied argument is not a valid MySQL result resource"?

The error message "Warning: mysql_fetch_array(): supplied argument is not a valid MySQL result resource" typically occurs when the query execution fails or returns an empty result set. To solve this issue, you should check if the query execution was successful before trying to fetch the results using mysql_fetch_array().

// Check if the query execution was successful
$result = mysql_query($query);
if(!$result) {
    die("Error in query: " . mysql_error());
}

// Fetch the results using mysql_fetch_array()
while($row = mysql_fetch_array($result)) {
    // Process the results
}