使用变量的SQL Update查询

Question

I am writing php to update a user's balance, but my UPDATE query seems to be throwing an error when it is executed.

    $student = $database->quote($_POST ["studentID"]);
    $amount = $database->quote($_POST ["update_balance"]);

    //sets query to update user balance
    $query = "UPDATE `User` SET `balance`= (`.$amount.`) WHERE `userID`= (`.$student.`)";
    //excecutes the query
    $database->exec($query);

The 'studentID' and 'update_balance' are names of input fields being captured in the HTML.

Answer 1

remove (`. things . and run sql query

$query = "UPDATE `User` SET `balance`= '$amount' WHERE `userID`= '$student'";