mysql_query returns TRUE for SELECT statement [closed]

The executing script does mostly nothing but call the following function. This problem doesn’t happen if I am not inserting anything beforehand (and just select the entire table).

function create_author()
{
    $config = config();

    $database = mysql_connect($config['database']['hostname'], $config['database']['username'], $config['database']['password']);
    mysql_select_db($config['database']['database']) || die('Cannot select database');

    $table = 'authors';
    $values = array();

    $values[] = sprintf(
        'first_name = "%s"',
        mysql_real_escape_string($_POST['first_name'])
    );
    if (array_key_exists('middle_initial', $_POST) && !empty($_POST['middle_initial'])) {
        $values[] = sprintf(
            'middle_initial = "%s"',
            mysql_real_escape_string($_POST['middle_initial'])
        );
    }
    $values[] = sprintf(
        'last_name = "%s"',
        mysql_real_escape_string($_POST['last_name'])
    );
    if (array_key_exists('biography', $_POST) && !empty($_POST['biography'])) {
        $values[] = sprintf(
            'biography = "%s"',
            mysql_real_escape_string($_POST['biography'])
        );
    }

    $query = sprintf(
        'INSERT INTO %s SET %s;',
        $table,
        implode(', ', $values)
    );

    mysql_query($query, $database) || die(mysql_error());

    $genre_id = mysql_insert_id($database);

    $query = sprintf(
        'SELECT * FROM authors WHERE id = %u LIMIT 1;',
        $genre_id
    );

    echo $query, PHP_EOL, '<br />', PHP_EOL;

    $result = mysql_query($query, $database) || die('Failed to read author.');

    //header('Content-Type: application/json');
    echo '$result: ', is_bool($result) ? ($result ? 'true' : 'false') : strval($result), PHP_EOL, '<br />', PHP_EOL;
    echo 'Number of selected rows: ', mysql_affected_rows($database), PHP_EOL, '<br />', PHP_EOL;
    echo 'Error: ', mysql_error($database), PHP_EOL, '<br />', PHP_EOL;

    mysql_close($database);

    echo json_encode(mysql_fetch_assoc($result));
}

This gives the following output:

---

SELECT * FROM authors WHERE id = 27 LIMIT 1;
$result: true
Number of selected rows: 1
Error:

Warning: mysql_fetch_assoc() expects parameter 1 to be resource, boolean given in file_path.php on line 89 null

---

Using a different SQL client, the above SELECT query returns a row. I am using PHP 5.3.3.

The “duplicate” questions don’t seem to answer the question.

Before the anti-mysql_* bandwagon rolls around the corner, I am using a server in which I have no control over for a school project. The server is controlled by the IT department. The pdo_mysql and mysqli extensions are not installed. Additionally, there are no other SQL extensions enabled except for the sqlite extension (which wouldn’t suffice since I need to use foreign keys). And the system administrator will not make changes. The point is that I have no choice but to use the mysql_* functions.

Answer

Using the || operator converts the result to a boolean value.