PHP PDO not deleting 2 fields from user table - php

Question

I'm trying to delete a username and password from a table using PDO. Below is the code that I'm using. It inserts fine, does everything else perfect. It's a script I've got from the internet. The most decent one I could find. But I'm very new to PHP PDO and need some help deleting a username and password from a table.
<?php
function dbconnect()
{
global $pdo;
try {
$pdo = new PDO('mysql:host=localhost;dbname=redgrace_staxapp', 'root', '');
} catch (PDOException $e) {
die('MySQL connection fail! ' . $e->getMessage());
}
}
function insert_new_user($username, $password)
{
# checking username is already taken
if (username_exists($username))
return FALSE;
# insert new user info
global $pdo;
$stmt = $pdo->prepare('
INSERT INTO users
(username, password)
values (:username, :password)');
$stmt->execute( array(':username' => $username, ':password' => md5($password)) );
if ($pdo->lastInsertId())
return true;
else
return false;
}
function delete_user($username, $password)
{
if (username_exists($username))
return FALSE;
global $pdo;
$stmt = "DELETE FROM users WHERE username = :username and password = :password";
$stmt->bindParam(':username', $username, PDO::PARAM_STR);
$stmt->bindParam(':password', $password, PDO::PARAM_STR);
$stmt->execute();
}
function username_exists($username)
{
global $pdo;
$stmt = $pdo->prepare('
SELECT id
FROM users
WHERE username = :username
LIMIT 1');
$stmt->execute( array('username' => $username) );
return $stmt->fetchColumn();
}
function attempt($username, $password)
{
global $pdo;
$stmt = $pdo->prepare('
SELECT id, username
FROM users
WHERE username = :username AND password = :password
LIMIT 1');
$stmt->execute(array(':username' => $username, 'password' => md5($password)));
if ($data = $stmt->fetch( PDO::FETCH_OBJ )) {
# set session
$_SESSION['username'] = $data->username;
return true;
} else {
return false;
}
}
function is_user()
{
if (isset($_SESSION['username']))
return true;
}
function redirect($url)
{
header('Location: ' .$url);
exit;
}
function valid_username($str){
return preg_match('/^[a-z0-9_-]{3,16}$/', $str);
}
function valid_password($str){
return preg_match('/^[a-z0-9_-]{6,18}$/', $str);
}
?>
Would be great if anyone can help me.

Answer 1

$stmt->bindParam(':username', $username);
$stmt->bindParam(':password', $password);
Do them one at a time (or use an array and execute)
http://us3.php.net/manual/en/pdostatement.bindparam.php
http://us3.php.net/manual/en/pdostatement.execute.php
$stmt->execute(['username'=>$username, 'password'=>$password]);

Answer 2

Try to find error if any like this (DETAILS: http://bd1.php.net/manual/en/pdo.errorinfo.php ):
global $pdo;
$sql = "DELETE FROM users WHERE username = :username and password = :password";
$stmt = $pdo->prepare($sql);
$stmt->bindParam(':username', $username);
$stmt->bindParam(':password', $password);
if (!$stmt) {
print_r($pdo->errorInfo());
}
$stmt->execute();

Answer 3

Try to change:
$stmt->bindParam(':username', $username, ':password', $password);
to:
$sth->bindParam(':username', $username, PDO::PARAM_STR);
$sth->bindParam(':password', $password, PDO::PARAM_STR);
I have tried again to edit your code, you don't need to use global variable, because you instantiate the PDO class directly and use it on the fly.
try {
$pdo = new PDO('mysql:host=localhost;dbname=redgrace_staxapp', 'root', '');
$pdo->setAttribute( PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION );
} catch (PDOException $e) {
die('MySQL connection fail! ' . $e->getMessage());
}
function delete_user($username, $password)
{
if (username_exists($username))
return TRUE;
$query = "DELETE FROM users WHERE username = :username and password = :password";
$stmt = $pdo->prepare($query);
$stmt->bindParam(':username', $username, PDO::PARAM_STR);
$stmt->bindParam(':password', $password, PDO::PARAM_STR);
$stmt->execute();
}