Redirect users to different pages based on role php

Question

Depending on the responsibilities that have been assigned to them in the database, I need to reroute users to various sites. On the login page, only the username and password are entered. I must retrieve the role from the database, which appears as follows:

username  |  password  |  role
xxxxxx       xxxxxx       admin
xxxxxx       xxxxxx       trainer
xxxxxx       xxxxxx       trainer
xxxxxx       xxxxxx       Line Manager

Here is my code:

// Connect to server and select databse.
mysql_connect("$host", "$username", "$password")or die("cannot connect"); 
mysql_select_db("$db_name")or die("cannot select DB");

// username and password sent from form 
$myusername=$_POST['myusername']; 
$mypassword=$_POST['mypassword']; 


$sql="SELECT * FROM login WHERE username='$myusername' and password='$mypassword'";
$result=mysql_query($sql);

// Mysql_num_row is counting table row
$count=mysql_num_rows($result);

// If result matched $myusername and $mypassword, table row must be 1 row
if($count==1){

     // Register $myusername, $mypassword and redirect to file "login_success.php"
     $role = mysqli_fetch_array($result);


      if($role == "Admin"){
        header("location:index.php");
            exit();
      }
      elseif($role['role'] == "Trainer"){
  header("location:index1.php");
        exit();
     }
      elseif($role['role'] == "Line Manager"){
  header("location:index2.php");
        exit();
     }
      elseif($role['role'] == "Client"){
  header("location:client.php");
        exit();
     }


  }
     else {
        echo "Wrong Username or Password"; 
     }
?>

Can someone help me with this?