PHP SQL 选择哪里和

Question

我不想在 MySQL 中保存双用户名和电子邮件，但现在这段代码不起作用，问题是什么？

我该怎么做？

function isUserExist($email,$userName){
    global $connect,$tbl_users;
    $email = sanitize($email);
    $userName = sanitize($userName);
    $sql = ("SELECT `email` FROM `$tbl_users` WHERE `email`=? AND `user_name`=?");
    $result = $connect->prepare($sql);
    $result->bindValue(1,$email);
    $result->bindValue(2,$userName);
    $result->execute();
    if ($result->rowCount()>=1){
        return $result;
    }

    return false;
}




<?php
    $query = null;
    $query_exist = null;

    if (isset($_POST['btn_submit'])) {
        $query_exist = isUserExist($_POST['email'],$_POST['userName']);
        if ($query_exist){
            echo 'A user with this email has already registered with the site to change your email and try again';
        }
        else {
            $query = createUser($_POST['firstName'], $_POST['lastName'], 
            $_POST['userName'], $_POST['password'], $_POST['email'], 
            $_POST['mobile'], $_POST['role']);
        }
    }

Answer 1

您应该分别检查电子邮件和用户名，您现在使用 AND 子句，因此返回 true 的唯一方法是用户名和电子邮件在行中匹配，但您不不想这样!

尝试切换到OR。这样，即使用户不匹配但电子邮件匹配，它也会返回 true，反之亦然。

您还可以稍微整理一下代码以摆脱这些全局变量:

function isUserExist($email,$userName, $connect, $tbl_users)
{
    $email = sanitize($email);
    $userName = sanitize($userName);
    $sql = "SELECT `email` FROM `$tbl_users` WHERE `email`=? AND `user_name`=?";
    $result = $connect->prepare($sql);
    $result->bindValue(1,$email);
    $result->bindValue(2,$userName);
    $result->execute();

    return $result->rowCount() >= 1;
}