How to avoid same userName in database?

[s3nzo]

Hi guys how do i avoid same user name being used more than once in a database? like if my database already has a user name s3nzo it must reject other registration with the same name or same email here is my code

<?php
    require    'inc/head.inc';
    
        $loginName    =    mysql_real_escape_string(htmlentities(stripslashes(trim($_POST['loginName']))));
        $email        =    mysql_real_escape_string(htmlentities(stripslashes(trim($_POST['email']))));
        $pass        =    mysql_real_escape_string(trim(htmlentities(stripslashes(trim(md5($_POST['pass']))))));
        $pas2        =    mysql_real_escape_string(trim(htmlentities(stripslashes(trim(md5($_POST['pas2']))))));
        $_SESSION['loginName']    =    $loginName;
        $_SESSION['email']        =    $email;
        $_SESSION['pass']        =    $pass;
    $sqle    =    "SELECT * FROM users";
    $querye    =    @mysql_query($sqle, $con);

            $errors    =    array();
                $fetch    =    @mysql_fetch_array($querye);
                    
                        if($_SESSION['loginName'] == $fetch['loginName'])
                            $errors    =    'Login name already taken';
                        if($_SESSION['email']        == $fetch['email'])
                            $errors    =    'Email address already in use';
                    
                if(empty($loginName))
                    $errors    =    'Login name can not be empty';
                if(empty($email))
                    $errors    =    'Email can not be empty';
                if(empty($pass) || empty($pas2))
                    $errors    =    'Both passwords are required';
                if($pass != $pas2)
                    $errors    =    'Passwords must be the same';
                    
                if(count($errors))
                    {
                        $_SESSION['errors']    =    $errors;

                        header('Location:register.php');
                    }
                else
                    {
                        $sql    =    "INSERT INTO users    SET    loginName    =    '{$_SESSION['loginName']}',
                                                            email        =    '{$_SESSION['email']}',
                                                            password    =    '{$_SESSION['pass']}',
                                                            id            =    '{NULL}',
                                                            nick        =    '{$_SESSION['loginName']}'";
                        if(!$query    =    @mysql_query($sql, $con))
                            $forms->showError();
                        else
                        {
                            $sql2    =    "SELECT * FROM users WHERE loginName    =    '{$_SESSION['loginName']}'";
                            if(!$query2    =    @mysql_query($sql2, $con))
                                $forms->showError();
                            else
                                {
                                    if(!$rows    =    @mysql_fetch_array($query2))
                                        $forms->showError();
                                        else
                                            {
                                                
                                                $_SESSION['id']            =    $rows['id'];
                                                $_SESSION['nick']                =    $rows['nick'];
                                                $_SESSION['fname']        =    $rows['fname'];
                                                $_SESSION['sname']        =    $rows['sname'];
                                                $_SESSION['perms']        =    $rows['permissions'];
                                                header('Location:home.php');
                                            }
                                }
                        }
                    }
                
    require    'inc/foot.inc';
?>

it rejects the registration of the same user name only once if you try again it inserts the details into database
################################################## #######################

NEVER mind guys problem solved

[something else]

eaiest way to prevent this from happening is to alter your sql:

ALTER TABLE users
ADD UNIQUE (loginName,email); 

[CreativityKills]

Then u myt in addition to what he said set database charset to UTF8. That way, sënzø and senzo are the same n cant be registered.