我必须对我的代码做些啥，以便它只会在数据库中不存在电子邮件的情况下创建帐户？ [复制]

Posted 2023-02-24

【中文标题】我必须对我的代码做些啥，以便它只会在数据库中不存在电子邮件的情况下创建帐户？ [复制]

【英文标题】：What do I have to do to my code so it will only create the account if the email doesn't already exist in the Database? [duplicate]我必须对我的代码做些什么，以便它只会在数据库中不存在电子邮件的情况下创建帐户？ [复制]

【发布时间】：2014-10-10 08:44:30

【问题描述】：

<?php
    $errorMessage = "";
    // start the session and register the session variables
    session_start("ProtectVariables");

    // get the command value (use request since both post and get are used
    $firstname = $_POST['firstNameZ'];
    $lastname = $_POST['lastNameZ'];
    $password = $_POST['passwordZ'];
    $email = $_POST['emailZ'];      

    $sql = "SELECT email FROM account WHERE email='" . $email . "'";
    $result = mysql_query($sql,$db);

    while ($myrow = mysql_fetch_array($result))            
        if  ($email == $myrow['email'])  
            $errorMessage = "Account with that email already exists";
         else 
            $errorMessage = "Email doesn't match!";
        
    
    if ($_POST['submit']) 
        $sql_insert = "INSERT INTO account (firstname,lastname,password,email) VALUES ('$firstname','$lastname','$password','$email')";
        $result_insert = mysql_query($sql_insert,$db);
    

?>

当我填写表格并点击提交时，即使电子邮件相同，它也只是插入到数据库中。我尝试将带有提交按钮的 if 语句放入 while 循环中，但这也不起作用。

【参考方案1】：

您可以更改条件以检查错误消息是否已填写：

if ($_POST['submit'] && $errorMessage == "Email doesn't match") 
    $sql_insert = "INSERT INTO account (firstname,lastname,password,email) VALUES ('$firstname','$lastname','$password','$email')";
    $result_insert = mysql_query($sql_insert,$db);

【讨论】：

if($_POST['submit'] && $errorMessage == "Email doesn't match!")

感谢您的帮助 dehrg！不幸的是，错误消息仍然出现 - “该电子邮件的帐户已经存在”。此外，即使电子邮件不同，它也不会向数据库添加任何内容。我不确定出了什么问题。你能再帮帮我吗？

gab06 是正确的！即使您成功了，我也没有看到您正在设置错误消息（考虑到变量的名称，这是不好的做法）请参阅我修改后的答案

【参考方案2】：

使用mysql_num_rows 函数来检查用户是否已经存在于数据库中。使用下面的代码

    <?php
        $errorMessage = "";
        // start the session and register the session variables
        session_start("ProtectVariables");

        // get the command value (use request since both post and get are used
        $firstname = $_POST['firstNameZ'];
        $lastname = $_POST['lastNameZ'];
        $password = $_POST['passwordZ'];
        $email = $_POST['emailZ'];      

        $sql = "SELECT email FROM account WHERE email='" . $email . "'";
        $result = mysql_query($sql,$db);

     if(mysql_num_rows($result)==0)
        if ($_POST['submit']) 
            $sql_insert = "INSERT INTO account (firstname,lastname,password,email) VALUES ('$firstname','$lastname','$password','$email')";
            $result_insert = mysql_query($sql_insert,$db);
        
    
else

echo "the user with this email address already exist";

    ?>

希望对你有帮助