Question

我已经检查了其他答案并尝试将其复制到我的答案中，但我收到了一个未经识别的row错误。

<?php
session_start();

if(isset($_SESSION['user_id'])) {
    header("Location: index.php");
}

include_once 'dbconnect.php';

//set validation error flag as false
$error = false;

//check if form is submitted
if (isset($_POST['signup'])) {
    $first_name = mysqli_real_escape_string($con, $_POST['first_name']);
    $last_name = mysqli_real_escape_string($con, $_POST['last_name']);
    $username = mysqli_real_escape_string($con, $_POST['username']);
    $email = mysqli_real_escape_string($con, $_POST['email']);
    $password = mysqli_real_escape_string($con, $_POST['password']);
    $cpassword = mysqli_real_escape_string($con, $_POST['cpassword']);
    $quote = mysqli_real_escape_string($con, $_POST['quote']);
    $who = mysqli_real_escape_string($con, $_POST['who']);

    //name can contain only alpha characters and space
    if ($_POST['username'] == $row['username']){
        $error = true;
        $username_error = '<div class="error-notice">
                            <div class="oaerror danger">
                            <strong>Uh oh!</strong> - Username is already in use.
                            </div>';

    }

Answer 1

没关系，我明白了。我必须在我的代码之上执行此操作。

$result = mysqli_query($con, "SELECT * FROM users WHERE username = '" . $username. "'");
    if($row = mysqli_fetch_array($result)){

检查用户名是否存在无效？

1 个答案: