Student residence management system

// Display User Name[Operation 1,2] 
$q="SELECT * from users where id ='".$_SESSION["id"]."'"; 
$result=mysql_query($q); 
$arr = mysql_fetch_array($result);
// Generate ref_no 
function generateRandStr($length){ 
$randstr = ""; 
for($i=0; $i<$length; $i++){ 
$randnum = mt_rand(0,61); 
if($randnum < 10){ 
$randstr .= chr($randnum+48); 
}else if($randnum < 36){ 
$randstr .= chr($randnum+55); 
}else{ 
$randstr .= chr($randnum+61); 
} 
} 
return $randstr; 
} 
// Make a booking 
if(isset($_POST['book'])) { 
// Check if student has already booked[Operation 4] 
$q = "SELECT * from booking WHERE user_id = '".$_SESSION['id']."'"; 
$result = mysql_query($q); 
$check = mysql_fetch_array($result); 
if($check){ 
echo ""; 
} 
else {
// Generate the ref number[Operation 5] 
$ref_no = generateRandStr(4); 
$student = $_SESSION["id"]; 
$q 
= 
"INSERT 
INTO 
booking 
VALUES('$ref_no','".$_SESSION['id']."','$room',now())"; 
$book = mysql_query($q); 

---

53 
// Get the room being booked 
$q = "SELECT booking.room_id from booking where user_id = 
'".$_SESSION["id"]."'"; 
$result = mysql_query($q); 
 
// Update room status 
$update = "UPDATE room SET status = 'pending' WHERE id = 
'".$room."'"; 
mysql_query($update);
// Send Email and SMS[Operation 6] 
$sql="select * from users where id = '".$student."'"; 
$Email = $arr['email'];
$Telephone = $arr['cell'];
$telephone= $Telephone; 
$from = ""; 
$to = "<".$student."@uwc.ac.za>,"; 
$to .= "<".$Email.">,"; 
$to .= "<".$telephone."@mtn.co.za>,"; 
$to .= "<".$telephone."@vodacom.co.za>,"; 
$to .= "<".$telephone."@cellc.co.za>,"; 
$subject = "Residence Booking Confirmation";