session check in php

include('config.php'); //connection file
session_start();
$user_check=$_SESSION['login_user'];
$ses_sql=mysql_query("select email from userdetails where email='$user_check' ");
$row=mysql_fetch_array($ses_sql);
$login_session=$row['email'];
$sesp_sql=mysql_query("select fname from userdetails where email='$user_check' ");
$rows=mysql_fetch_array($sesp_sql);
$login_session1=$rows['fname'];
if(!isset($login_session))
{

}
else
{
header("Location:../home.php");
}
?>