Insert data into Database using php PDO - php

Question

I'm trying to create a "registration" form using php and mysql. The registration form asks for username and password. If any field is empty, it will let the user know which one. If the username is in use, it will also let the user know.
I know the connection to the database is ok, because I created a user that was I manually added into the database.
The strange thing is that my code is working in Cloud9. But, it wont work on a VM instance installed on google cloud.
In cloud9, it adds the user into the DB. In the google instance, it wont.
Can anyone check this and tell me what I;m doing wrong?
Thanks.
<?php
$username = $_POST['username'];
$password = $_POST['password'];
$display = $_POST['display'];
$dbh = new PDO("mysql:host=localhost;dbname=mydb","root",NULL);
$stmt = $dbh->prepare("SELECT username FROM users WHERE username = :username");
$stmt->bindParam(':username', $username);
$stmt->execute();
if($stmt->rowCount() == 0 and $username != null and $password != null){
$insert = $dbh->prepare("INSERT INTO users(username,password) VALUES(:username, :password)");
$insert->bindParam(':username', $username);
$insert->bindParam(':password', $password);
$insert->execute();
echo ("The user ".$username. " has been created.");

Answer 1

Try this, before all u need to check
if username and password is not empty because if username is empty i
cant make query valid to select username
check if username is in use
if username not in use, insert data into database
script
<?php
// error_reporting on
error_reporting(1);
ini_set('error_reporting', E_ALL);
$username = $_POST['username'];
$password = $_POST['password'];
// i commented $display variable because i don't see that u using it anywhere
//$display = $_POST['display'];
// database connection
$dbh = new PDO("mysql:host=localhost;dbname=mydb","root","");
// query
$stmt = $dbh->prepare("SELECT username FROM users WHERE username = :username");
$stmt->bindParam(':username', $username);
$stmt->execute();
// check if username and password is not empty
if ($username != '' && $password != '')
{
// check if username is in use
if($stmt->rowCount() > 1)
{
echo "Username in use, please choose another one.";
}
else
{
$insert = $dbh->prepare("INSERT INTO users(username,password) VALUES(:username, :password)");
$insert->bindParam(':username', $username);
$insert->bindParam(':password', $password);
$insert->execute();
// if last inserted id is true
if ($dbh->lastInsertId())
{
echo "The user ".$username. " has been created.";
}
else
{
echo "User not registered, please try again.";
}
}
}
else
{
echo "Please enter username and password.";
}
?>