php - 检查重复的数据库条目

Question

我最近一直在做一个表格。它工作正常。我只想对其添加一个调整，如果注册一个已经在数据库中注册的电子邮件 ID，它会显示错误。这是我的整个 PHP 代码::

<?php
      //include the connection file

      require_once("validation.php");

if( isset($_POST['send']) && (!validateName($_POST['name']) || !validateEmail($_POST['email']) || !validatePasswords($_POST['pass1'], $_POST['pass2']) || !validateContact($_POST['contact']) || !validateAge($_POST['age'])) ):?>
            <div id="error">    
                <ul>
                    <? if(!validateName($_POST['name'])):?>
                        <li><strong>Invalid Name:</strong> We want names with more than 3 letters.</li>
                    <? endif?>
                    <? if(!validateEmail($_POST['email'])):?>
                        <li><strong>Invalid E-mail:</strong> Type a valid e-mail please.</li>
                    <? endif?>
                    <? if(!validatePasswords($_POST['pass1'], $_POST['pass2'])):?>
                        <li><strong>Passwords are invalid:</strong> Passwords doesnt match or are invalid!</li>
                    <? endif?>
                    <? if(!validateContact($_POST['contact'])):?>
                        <li><strong>Please enter a valid number.</strong></li>
                    <? endif?>
                    <? if(!validateAge($_POST['age'])):?>
                        <li><strong>Please enter a valid age</strong></li>
                    <? endif?>
                    <? if(!validateWork($_POST['work'])):?>
                        <li><strong>Please enter work</strong></li>
                    <? endif?>
                    </ul>
            </div>
        <?php elseif(isset($_POST['send'])):?>
            <div id="error" class="valid">
                <ul>
                <?php
                require_once('connection.php'); 
                $query = "INSERT INTO employee (name, password, email, contact, age, gender, location, skill, work) VALUES ";                           
                $query .= "('".$_POST['name']."', '".$_POST['pass1']."', '".$_POST['email']."','".$_POST['contact']."','".$_POST['age']."','".$_POST['gender']."','".$_POST['location']."','".$_POST['skill']."','".$_POST['work']."')";
                // run the query
                mysql_query($query);?>
                <li><strong>Congratulations!</strong> You have been successfully registered!</li>
                </ul>
            </div>
    <?php endif?>

Answer 1

您可以给电子邮件字段一个 UNIQUE 约束，这样就不会出现重复。在这种情况下，INSERT 查询将失败，您的查询将返回 false。

if (!mysql_query($query)) {
    // Error, email already exists, no data was inserted
} else {
    // Successfully inserted row, print success message.
}

INSERT 查询实际上会失败，而不仅仅是返回 0 行已修改。