อธิบายโค๊ดนี้ใหม่หน่อยคะ อยากทราบว่า ทำงานยังไง การดึงฐานยังไง งง มากเลย

<?php
require_once('Connections/mai_inn.php');
$ncount = $_POST['nbox'];
if ($ncount == 0){
	exit;
}
$cccount[0]=0;
$foryear[0]="name_subject";
$foryear[1]="id_subject";
$foryear[3]="credit";
for ($i = 0; $i < $ncount; $i++) {
	$dsf = "checkbox_".$i;	
		if($_POST[$dsf]){
		 
		$cccount[] = $i;
	}
}
$body_echo = "";
$body_echo .="<table width='100%' border='2' cellpadding='2'>";
$body_echo .="<tr>";
$body_echo .="<th scope='col'>ป.ตรี สาขาวิชาระบบสาระสนเทศฯ</th>";
$body_echo .="<th scope='col'>รหัสวิชา</th>";
$body_echo .="<th scope='col'>หน่วยกิจ</th>";
$body_echo .="<th scope='col'>หมายเหตุ</th>";
$body_echo .="<th scope='col'>วิชาอาชีวะของคุณ</th>";
$body_echo .="<th scope='col'>รหัสวิชา</th>";
$body_echo .="<th scope='col'>หน่วยกิจ</th>";
$body_echo .="</tr>";
$body_echo .="<tr>";
foreach($cccount as $val){
	
	//echo $val;

			mysql_select_db($database_mai_inn, $mai_inn);
			$strq="SELECT * FROM vocational_education WHERE id = '".$val."'";
			$tracut1 = mysql_query($strq, $mai_inn) or die(mysql_error());
			 mysql_query("SET NAMES UTF8");
 			 mysql_query("SET character_set_results=utf8");
			 mysql_query("SET character_set_client=utf8");
			 mysql_query("SET character_set_connection=utf8");			
			while ($rec1 = mysql_fetch_assoc($tracut1)){
			$tess= $rec1['according2'];
			$str_4year_information="SELECT * FROM transferdegree_4year_information WHERE use_boo = '1' AND according = '".$rec1['according1']."' LIMIT 0 , 1";
			$tracut2 = mysql_query($str_4year_information, $mai_inn) or die(mysql_error());	
			while ($rec = mysql_fetch_assoc($tracut2)){
				$strq3="SELECT * FROM vocational_education WHERE according2 ='".$tess."'";
				$tracut3 = mysql_query($strq3, $mai_inn) or die(mysql_error());		
				$Rows_t = mysql_num_rows($tracut3);		
				    $body_echo .="<td rowspan='".$Rows_t."'>".$rec['name_subject']."</td>";
				    $body_echo .="<td rowspan='".$Rows_t."'>".$rec['id_subject']."</td>";
				    $body_echo .="<td rowspan='".$Rows_t."'>".$rec['credit']."</td>";
				    $body_echo .="<td rowspan='".$Rows_t."'>".$rec['comment']."</td>";
				while ($rec3 = mysql_fetch_assoc($tracut3)){
					$body_echo .="<td>".$rec3['name_subject']."</td>";
				    $body_echo .="<td>".$rec3['id_subject']."</td>";
				    $body_echo .="<td>".$rec3['credit']."</td>";				
					if ($Rows_t >1){
				    $body_echo .="</tr>";
				    $body_echo .="<tr>";
					}
				}
				    $body_echo .="</tr>";
			}
			}


}
$body_echo .="</table>";
?>