Question

I managed to run the following code to insert into my table on first try. Then, I deleted that row in PHPMyAdmin to test my code further. I also noticed that it didn’t get deleted on the 1st try. Only after few try. This might be due to I didn’t set the $pdoHandle to NULL after I’m done with the query.

Then, unfortunately I couldn’t insert new row on subsequent run. I even tried to change the input value and to avail I was unable to insert new row. The following are my PHP codes:

public function CreateNewCustomer($userId,$password,$name,$email)
{
    $userId = filter_var($userId,FILTER_SANITIZE_STRING);
    $password = filter_var($password,FILTER_SANITIZE_STRING);
    $password = sha1($password);
    $name = filter_var($name,FILTER_SANITIZE_STRING);
    $email = filter_var($email,FILTER_SANITIZE_EMAIL);

    do{
        $customerId = hexdec(bin2hex(openssl_random_pseudo_bytes(4,$isStrong)));
        echo $customerId;
        $result = $this->connObject->exec("SELECT COUNT(id) FROM customer_tbl WHERE id=$customerId");
        var_dump($result);
    }while($result>0);

    $statement = $this->connObject->prepare("INSERT INTO customer_tbl (id,name,email) VALUES ($customerId,:name,:email)");
    $result = $statement->execute(array(':name'=>$name,':email'=>$email ));
    var_dump($result);

    $statement = $this->connObject->prepare("INSERT INTO login_tbl (username,password,customer_id) VALUES (:userName,PASSWORD(:password),$customerId)");
    $result = $statement->execute(array(':userName'=>$userId,':password'=>$password ));
    var_dump($result);
}

I used the following code to access the above method.

function Test($userName,$password,$name,$email)
{
try
{
    $dbConnect = new DbConnect();
    $pdoHandle = $dbConnect->Connect();
    $userAccess = new UserAccess($pdoHandle);
    $userAccess->CreateNewCustomer($userName,$password,$name,$email);
}
catch(PDOException $e)
{
    $pdoHandle = null;
    var_dump($e);
}
$pdoHandle = null;
}

Test('tester','password','TestX','[e-mail]');

The var_dump of results is always false.

Is there any problem with my codes or is it something wrong with the database?

UPDATE/SOLUTION:

I just read through the PHP document on PDO::exec() and one of the user contributed notes mentioned that you can’t use any SELECT statements (even thou the above only returns the count value) and any statements which might return a rows. The return value of PDO::exec() is the number of affected rows (integer), so the PDOStatement::closeCursor() can’t be used to solve it. Even when I set the PDO::MYSQL_ATTR_USE_BUFFERED_QUERY=>true, it still doesn’t work.

So, don’t use PDO::exec() for any SELECT. I changed my code to PDO::query() instead as below,

   do{
        $customerId = hexdec(bin2hex(openssl_random_pseudo_bytes(4,$isStrong)));
        $statement = $this->connObject->query("SELECT COUNT(id) FROM customer_tbl WHERE id=$customerId");
        $statement->execute();
    }while($statement->fetchColumn(0)>0);

Hope this would be helpful to anyone looking for a solution with similar problem and always remember to read the PHP document first including the user contributions.

Answer 1

Maybe not the answer but here are some things that you can do if you cannto see an obvious error:

If execute returns false, you can get more information about the error that happened by:

$arr = $statement->errorInfo(); 
print_r($arr);

or you can set different error reporting modes (e.g. throw an exception instead of the defaultsilent mode):

$dsn = 'mysql:dbname=testdb;host=127.0.0.1';
$user = 'dbuser';
$password = 'dbpass';
$dbh = new PDO($dsn, $user, $password);
$dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

This should help you to find the “real” error.

As it turned out (see comments below question), in this case the real error was:

“Cannot execute queries while other unbuffered queries are active.
Consider using PDOStatement::fetchAll(). Alternatively, if your code
is only ever going to run against mysql, you may enable query
buffering by setting the PDO::MYSQL_ATTR_USE_BUFFERED_QUERY”

In this case you have 2 options:

you can set the option to use buffered queries

$dbh = new PDO(’mysql:host=localhost;dbname=test’, ‘root’, ” ,array(PDO::MYSQL_ATTR_USE_BUFFERED_QUERY => true)) 

or change your code and close an open cursor (may depend on the db driver you are using). You always should read the documentation which covers a lot of default problems.

Hope this helps.