检查数据库中是否存在用户名的方法

Question

I have this method which checks if a username exists in the database:

public function checkUsername($username) 
{

    global $wpdb;
    $result = $wpdb->get_row( "SELECT * FROM {$wpdb->prefix}users WHERE con_username =".$username);
    if(!empty($result)){

        return false;
    }

}

I am then checking the username like so:

if(!$users->checkUsername($_POST['email'])){
        $error++;
        $error_msg[]='Email already exists!';
    }

However this isnt working as it is telling me that every username i try already exists. I dont think i have the returns written correctly.. Any ideas??

Answer 1

You are not returning anything if the email not found and so checkUsername will return null in this case.

$users->checkUsername($_POST['email']) will always empty or null .

Try with -

return empty($result);

The function should be -

public function checkUsername($username) 
{

    global $wpdb;
    $result = $wpdb->get_row( "SELECT * FROM {$wpdb->prefix}users WHERE con_username ='".$username."'");
    return empty($result);

}

And check -

if(!$users->checkUsername($_POST['email'])){

And try to implement some security to input data.