สอบถามเรื่องการเขียนโค้ดแสดงผล ให้เช็คจาก username ที่เข้าล็อกอิน

$strSQL  = "SELECT * FROM booking";
$strSQL .= " LEFT JOIN personal ON booking.personal_id = personal.personal_id";
$strSQL .= " WHERE personal.username = '".$_SESSION['username']."'";

<?php

mysql_select_db($dbname, $connect);
$query = "SELECT
status_booking.status_booking_id,
status_booking.status_booking_name,
booking.status_booking_id,
time.time_id,
time.time,
room.room_id,
room.room_name,
booking.booking_id,
booking.room_id,
booking.time_id,
booking.booking_date,
personal.personal_id,
personal.username,
personal.`name`,
booking.personal_id
FROM
booking
INNER JOIN status_booking ON status_booking.status_booking_id = booking.status_booking_id
INNER JOIN time ON time.time_id = booking.time_id
INNER JOIN room ON room.room_id = booking.room_id
INNER JOIN personal ON personal.personal_id = booking.personal_id WHERE personal.username = '".$_SESSION['username']."' "; 
$query_db = mysql_query($query, $connect) or die(mysql_error());
$row_db = mysql_fetch_assoc($query_db);
?>

<?php
@session_start();
include "connect.php";
$id=$_SESSION[username];
$sql=mysql_query("SELECT * from personal WHERE username='$username' ");
$result = mysql_fetch_array($sql);
$personal_id = $result[personal_id];
$txtname = $result[name];
$txtsname = $result[sname];
$username =$result[username];
$_SESSION['username'] = $username;
$_SESSION['personal_id'] = $personal_id;
if(empty($username))
{
echo "<script>alert('กรุณาล็อกอินก่อนเข้าใช้งานด้วยครับ');</script>";
echo "<script type='text/javascript'>window.location=\"login.html\"</script>";
exit();
}
?>