จัดระเบียบซอร์สโค๊ด PHP เพื่อลดจำนวนการ Query ฐานข้อมูล MySQL น้อยลง

<?php
$no = 0;
$sql = "SELECT * FROM booking WHERE month = '04' ";
$result = mysql_query($sql);//คิวรี่ครั้งที่ 1
while( $rs = mysql_fetch_assoc($result) ){
 
 $dpId = $rs["book_department_id"];
       //คิวรี่ครั้งที่ 2
 $qry = mysql_query("SELECT department_name FROM tb_department WHERE department_id = '".$dpId."' ");
 $rsDp = mysql_fetch_assoc($qry);
 $departMentName = $rsDp["department_name"];
 
 echo "<br/>", $departMentName;
}
?>

<?php
//รายชื่อแผนกทั้งหมด
$allDepart = array();
$qry = mysql_query("SELECT department_id, department_name FROM tb_department");
while($rsDp = mysql_fetch_assoc($qry)){
 $allDepart[$rsDp['department_id ']] = $rsDp['department_name']
}
 
$no = 0;
$sql = "SELECT * FROM booking WHERE month = '04' ";
$result = mysql_query($sql);
while( $rs = mysql_fetch_assoc($result) ){
 
 $dpId = $rs["book_department_id"];
 $departMentName = $allDepart[$dpId];
  
 echo "<br/>", $departMentName;
}
?>