How can I use prepared statements combined with Transactions with PHP?

Question

My goal is to use a transaction and a prepared statement simultaneously, to achieve both integrity of data, and prevention of SQL injection.

I have this:

<         


        

Answer 1

Did you mean this?

try {
    $cnx = new PDO($dsn,$dbuser,$dbpass);   
    $cnx->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

    $cnx->beginTransaction();
    $stmt=$cnx->prepare("
        SELECT * FROM users, othertable 
        WHERE users.username=? 
        AND othertable.some_column=?");

    $stmt->execute(array($user_input,$user_input_2));

    $cnx->commit();
}
catch (Exception $e){
       $cnx->rollback();
       echo "an error has occured";
}

That is assuming that the two tables data does not have duplicate field names, otherwise you're going to have to use:

SELECT users.field1 as u_field1, othertable.field1 as o_field1 FROM users, othertable 
WHERE users.username=? 
AND othertable.some_column=?