php - select查询中的where条件

Question

我必须检查用户名和电子邮件(如果两者中的任何一个已经存在)，

当我在 where 条件中添加 OR 时，它始终处于 IF 条件中。

代码:

$fetch_user=mysql_query("SELECT userid FROM users WHERE username ='".$username."' OR email='".$email."'") or die(mysql_error());
if(mysql_num_rows($fetch_user))
{ 
    echo '<font color="red">The nickname <strong>'.$username.''.$email.'</strong>'.' is already in use.</font>';
} 
else 
{
    $query = mysql_query("insert into users values ('','$username','$email','$password','','$roll')") or die(mysql_error());
    if($query)
    {
        echo 'Successfully Inserted';
    }
    else
    {
        echo 'Insertion Faild';
    }
}

感谢您的帮助!

Answer 1

我没有发现代码有任何问题。但我只能看到逻辑是错误的。如果用户名或电子邮件已存在，您将显示一条消息:昵称用户名和电子邮件已在使用中。可能只有用户名已在使用，但电子邮件尚未使用，反之亦然。因此，您需要向用户显示正确的消息，哪一张被拍摄，哪一张未被拍摄。

<?php 
$userNameTaken = false;
$emailTaken = false;

//check if username exists
$checkUsername = mysql_query("SELECT userid FROM users WHERE username ='".$username."'") or die(mysql_error());
if(mysql_num_rows($checkUsername))
{ 
    $userNameTaken = true;
}

//check if email exists
$checkEmail = mysql_query("SELECT userid FROM users WHERE email ='".$email."'") or die(mysql_error());
if(mysql_num_rows($checkEmail))
{ 
    $emailTaken = true;
}

if($userNameTaken || $emailTaken) //if any of username or email taken
{
    if($userNameTaken && $emailTaken) //username and email both taken
    {
        echo '<font color="red">The username <strong>'.$username.'</strong> and email <strong>'.$email.'</strong> already in use.</font>';
    }
    else if($userNameTaken && !$emailTaken) //only username taken
    {
        echo '<font color="red">The username <strong>'.$username.'</strong> is already in use.</font>';
    }
    else if(!$userNameTaken && $emailTaken) //only email taken 
    {
        echo '<font color="red">The email <strong>'.$email.'</strong> is already in use.</font>';
    }
} 
else 
{
    $query = mysql_query("insert into users values ('','$username','$email','$password','','$roll')") or die(mysql_error());
    if($query)
    {
        echo 'Successfully Inserted';
    }
    else
    {
        echo 'Insertion Faild';
    }
}
?>