Question

我环顾四周，已经看过很多例子，但很遗憾无法将其实现到我目前正在使用的代码中。

我想阻止用户在我的网页上注册时使用相同的用户名，但我使用的代码允许这些条目相同。

如何修改以下代码以防止这种情况发生？

 <?php
            require('db.php');
            // If form submitted, insert values into the database.
            if (isset($_POST['username'])){
                $username = $_POST['username'];
                $email = $_POST['email'];
                $password = $_POST['password'];
                $username = stripslashes($username);
                $username = mysql_real_escape_string($username);
                $email = stripslashes($email);
                $email = mysql_real_escape_string($email);
                $password = stripslashes($password);
                $password = mysql_real_escape_string($password);
                $trn_date = date("Y-m-d H:i:s");

                $res_login = $conn->query("select * from users where username='$username'");
                if($res_login -> num_rows > 0)
                {
                      echo "Username is already exists please try with another username";
                }
                else
                {
                      $query = "INSERT into `users` (username, password, email, trn_date) VALUES ('$username', '".md5($password)."', '$email', '$trn_date')";
                      $result = mysql_query($query);
                      if($result)
                      {
                                  echo "You are registered successfully.</h3><br/>Click here to <a href='login.php'>Login</a></div>";
                      }
                      else
                      {
                                  echo "error in registration";
                      }
                }
         }
        ?>

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Answer 1

最好的方法是在您的数据库中将用户名设置为主键，这会让您在复制时出错。

用您的代码回答您的问题，就是搜索用户名，如果存在，请不要添加。

无论如何，你的问题是重复的。 Here

Answer 2

检查唯一性的最佳方法是，您必须在数据库中将用户名设置为主键，但如果要手动检查，则使用选择查询检查数据库中是否存在用户名？

      <?php
            require('db.php');
            // If form submitted, insert values into the database.
            if (isset($_POST['username'])){
                $username = $_POST['username'];
                $email = $_POST['email'];
                $password = $_POST['password'];
                $username = stripslashes($username);
                $username = mysql_real_escape_string($username);
                $email = stripslashes($email);
                $email = mysql_real_escape_string($email);
                $password = stripslashes($password);
                $password = mysql_real_escape_string($password);
                $trn_date = date("Y-m-d H:i:s");

                $res_login = mysql_query("select * from users where username='$username'");
                $sql_num = mysql_num_rows($res_login);
                if($sql_num > 0)
                {
                      echo "Username is already exists please try with another username";
                }
                else
                {
                      $query = "INSERT into `users` (username, password, email, trn_date) VALUES ('$username', '".md5($password)."', '$email', '$trn_date')";
                      $result = mysql_query($query);
                      if($result)
                      {
                                  echo "You are registered successfully.</h3><br/>Click here to <a href='login.php'>Login</a></div>";
                      }
                      else
                      {
                                  echo "error in registration";
                      }
                }
         }
        ?>

请使用准备好的声明进行最佳编程练习。访问此链接： PDO::prepare manual

Answer 3

您还可以将用户名设置为唯一键索引，以防止在表格中输入重复的行。

并查看以下代码

<?php
    require('db.php');
    // If form submitted, insert values into the database.
    if (isset($_POST['username'])){
        $username = $_POST['username'];
        $email = $_POST['email'];
        $password = $_POST['password'];
        $username = stripslashes($username);
        $username = mysql_real_escape_string($username);
        $email = stripslashes($email);
        $email = mysql_real_escape_string($email);
        $password = stripslashes($password);
        $password = mysql_real_escape_string($password);
        $trn_date = date("Y-m-d H:i:s");
        $query = "INSERT into `users` (username, password, email, trn_date) VALUES ('$username', '".md5($password)."', '$email', '$trn_date')";
        $result = mysql_query($query);
        if (mysql_errno()) {
           if (mysql_errno()==1062) {
              echo "Username already taken.";
           }
        }else{
            if($result){
            echo "You are registered successfully.</h3><br/>Click here to <a href='login.php'>Login</a></div>";
        }
        }
    }else{
?>

希望这对你有用....

注册时防止重复的用户名条目（PHP / MySQL

3 个答案: