Number of variables doesn't match number of parameters in prepared statements

Question

$sql = "SELECT table_name FROM information_schema.tables WHERE table_schema = '?'";
$stmt = $db->prepare($sql);
$stmt->bind_param("s", $database);
$stmt->execute();
$resultSet = $stmt->get_result();

It says " Warning : mysqli_stmt::bind_param(): Number of variables doesn't match number of parameters in prepared statement in..."

Can somebody explain what's wrong? $database is a string.

Answer 1

If you use ? as a placeholder, don't use ticks ' s

$sql = "SELECT table_name FROM information_schema.tables WHERE table_schema = ?";
$stmt = $db->prepare($sql);
$stmt->bind_param('s', $database);
$stmt->execute();
$resultSet = $stmt->get_result();