人们注册时如何防止重复的用户名? [英] How to prevent duplicate usernames when people register?

问题描述

我一直在做一个登录/注册系统，我接近完成我的代码注册部分.我遇到的唯一问题是如何使用户无法使用重复的用户名进行注册.我希望它能正常工作，以便我的数据库不接受该信息，并且它将告诉用户该错误.

I have been making a login/register system and I am drawing close to finishing my register portion of code. The only problem I am running into is how to make it so that users cannot register with duplicated usernames. I want it to work so that my database won't accept the information, and it will tell the user about the error.

我的PHP

<?php

include 'database_connection.php';
if (isset($_POST['formsubmitted'])) {
    $error = array(); //Declare An Array to store any error message
if (empty($_POST['name'])) {//if no name has been supplied
    $error[] = 'Please Enter a name '; //add to array "error"
} else {
    $name = $_POST['name']; //else assign it a variable
}

    if (empty($_POST['e-mail'])) {
        $error[] = 'Please Enter your Email ';
    } else {
        if (preg_match("/^([a-zA-Z0-9])+([a-zA-Z0-9\._-])*@([a-zA-Z0-9_-])+([a-zA-Z0-9\._-]+)+$/", $_POST['e-mail'])) {
            //regular expression for email validation
            $Email = $_POST['e-mail'];
        } else {
            $error[] = 'Your EMail Address is invalid  ';
        }
    }

    if (empty($_POST['Password'])) {
        $error[] = 'Please Enter Your Password ';
    } else {
        $Password = $_POST['Password'];
    }

    if (empty($error)) {
        //send to Database if there's no error '
    }
}

推荐答案

例如，当用户发布用户名并单击提交"时，您可以执行以下操作:/p>

You can do it like this when the user post the username for example and click submit you can write this code or add it to your code with your modification :

<?php

$connect = mysql_connect('whatever', 'whatever', 'whatever');
$database = mysql_select_db('your dbname');
$username = $_POST['username'];
if (isset($username)) {
    $mysql_get_users = mysql_query("SELECT * FROM table_name where username='$username'");

    $get_rows = mysql_affected_rows($connect);

    if ($get_rows >= 1) {
        echo "user exists";
        die();
    } else {
        echo "user do not exists";
    }
}

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