mysql - php login system do not stop or send any error messages when users login incorrectly -

when coded php login system (in mysqli), error not checks if username or password wrong, idk abot this. please me out here.

<?php // if logged in     if(isset($_session['user_id'])) {         header('location: index.php');     }else {} //error_reporting(0); //mysqli login form     //database connection     $con = mysqli_connect('localhost', 'root', '', 'console');  //actual login form         if(isset($_post['login'])) {             session_start();             //explainging details                 $username = $_post['username'];                 $password = $_post['password'];               //fetching data                 $result = $con->query("select * users username='$username' , password='$password'");                 $row = $result->fetch_array(mysqli_both);              //logging in                 $_session['user_id'] = $row['user_id'];                 header('location: index.php');          }else{             $wrong = 'username or password wrong';         } ?> 

also got check.php redirects /notloggedin.php if not logged in, if user logged in display user_id, when user logsin wrong details go check.php not show , not redirect users /notloggedin.php.

do that? there forgot add, or did wrong???


can write example if have ideas?? thanks.

edit:
instead of using mysqli got idea @christoandrew, made functions. functions tells system gonna check username first, if username exists gonna make $_session()for username. again using $_session() find user_id username gonna password same user_id. when checked destroy 'sessions' made , create $_session() information user_id, email, username, password, etc... got in way!

if(isset($_post['login'])) {             session_start();             //explainging details                 $username = $_post['username'];                 $password = $_post['password'];           //fetching data             $result = $con->query("select * users username='$username' , password='$password'");             $row = $result->fetch_array(mysqli_both);         // try checking if there rows returned         // if rows greater 0 user exists else         // user supplied wrong credentials         if(mysqli_num_rows($row) > 0){             //logging in             $_session['user_id'] = $row['user_id'];             header('location: index.php');         }else{           $wrong = 'username or password wrong';         }       // else block below not necessary , validation misplaced     }