Why Can't I Use Parameters in the ORDER BY Clause of My Prepared PDO Statement?

Usability of Params in ORDER BY Clause with Prepared PDO Statement

In your SQL statement, you encounter difficulties when employing params within the ORDER BY clause. Despite binding params to the :order and :direction placeholders, the statement executes without output.

Unlike the :my_param placeholder, which functions properly, the :order and :direction placeholders necessitate direct insertion into the SQL. You can do this as follows:

$order = 'columnName';
$direction = 'ASC';

$stmt = $db->prepare("SELECT * from table WHERE column = :my_param ORDER BY $order $direction");

There is no PDO::PARAM_COLUMN_NAME constant or similar substitute. The caveat is that all operators and identifiers in the ORDER BY clause must be hardcoded. For instance:

$orders = array("name", "price", "qty");
$key = array_search($_GET['sort'], $orders);
$order = $orders[$key];
$query = "SELECT * from table WHERE is_live = :is_live ORDER BY $order";

Whitelisting, shown below, is an alternative approach that safeguards against invalid input:

$order = white_list($order, ["name", "price", "qty"], "Invalid field name");
$direction = white_list($direction, ["ASC", "DESC"], "Invalid ORDER BY direction");

$sql = "SELECT field from table WHERE column = ? ORDER BY $order $direction";
$stmt = $db->prepare($sql);
$stmt->execute([$is_live]);

This ensures that incorrect values are flagged and handled gracefully, enhancing the security of your application.

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