registration page database query code example

Example 1: php user login and registration

<?php
session_start();

// initializing variables
$username = "";
$email    = "";
$errors = array(); 

// connect to the database
$db = mysqli_connect('localhost', 'root', '', 'registration');

// REGISTER USER
if (isset($_POST['reg_user'])) {
  // receive all input values from the form
  $username = mysqli_real_escape_string($db, $_POST['username']);
  $email = mysqli_real_escape_string($db, $_POST['email']);
  $password_1 = mysqli_real_escape_string($db, $_POST['password_1']);
  $password_2 = mysqli_real_escape_string($db, $_POST['password_2']);

  // form validation: ensure that the form is correctly filled ...
  // by adding (array_push()) corresponding error unto $errors array
  if (empty($username)) { array_push($errors, "Username is required"); }
  if (empty($email)) { array_push($errors, "Email is required"); }
  if (empty($password_1)) { array_push($errors, "Password is required"); }
  if ($password_1 != $password_2) {
	array_push($errors, "The two passwords do not match");
  }

  // first check the database to make sure 
  // a user does not already exist with the same username and/or email
  $user_check_query = "SELECT * FROM users WHERE username='$username' OR email='$email' LIMIT 1";
  $result = mysqli_query($db, $user_check_query);
  $user = mysqli_fetch_assoc($result);
  
  if ($user) { // if user exists
    if ($user['username'] === $username) {
      array_push($errors, "Username already exists");
    }

    if ($user['email'] === $email) {
      array_push($errors, "email already exists");
    }
  }

  // Finally, register user if there are no errors in the form
  if (count($errors) == 0) {
  	$password = md5($password_1);//encrypt the password before saving in the database

  	$query = "INSERT INTO users (username, email, password) 
  			  VALUES('$username', '$email', '$password')";
  	mysqli_query($db, $query);
  	$_SESSION['username'] = $username;
  	$_SESSION['success'] = "You are now logged in";
  	header('location: index.php');
  }
}

// ...

Example 2: how to make a sign-up database

<html>
<head>
<title>PHP User Registration Form</title>
<link href="./css/style.css" rel="stylesheet" type="text/css" />
</head>
<body>
    <form name="frmRegistration" method="post" action="">
        <div class="demo-table">
        <div class="form-head">Sign Up</div>
            
<?php
if (! empty($errorMessage) && is_array($errorMessage)) {
    ?>	
            <div class="error-message">
            <?php 
            foreach($errorMessage as $message) {
                echo $message . "<br/>";
            }
            ?>
            </div>
<?php
}
?>
            <div class="field-column">
                <label>Username</label>
                <div>
                    <input type="text" class="demo-input-box"
                        name="userName"
                        value="<?php if(isset($_POST['userName'])) echo $_POST['userName']; ?>">
                </div>
            </div>
            
            <div class="field-column">
                <label>Password</label>
                <div><input type="password" class="demo-input-box"
                    name="password" value=""></div>
            </div>
            <div class="field-column">
                <label>Confirm Password</label>
                <div>
                    <input type="password" class="demo-input-box"
                        name="confirm_password" value="">
                </div>
            </div>
            <div class="field-column">
                <label>Display Name</label>
                <div>
                    <input type="text" class="demo-input-box"
                        name="firstName"
                        value="<?php if(isset($_POST['firstName'])) echo $_POST['firstName']; ?>">
                </div>

            </div>
            <div class="field-column">
                <label>Email</label>
                <div>
                    <input type="text" class="demo-input-box"
                        name="userEmail"
                        value="<?php if(isset($_POST['userEmail'])) echo $_POST['userEmail']; ?>">
                </div>
            </div>
            <div class="field-column">
                <div class="terms">
                    <input type="checkbox" name="terms"> I accept terms
                    and conditions
                </div>
                <div>
                    <input type="submit"
                        name="register-user" value="Register"
                        class="btnRegister">
                </div>
            </div>
        </div>
    </form>
</body>
</html>

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