ช่วยแนะนำเกี่ยวกับการรับค่าจาก List/Menu หน่อยครับ ว่าเขียนยังไง

 <?
	 
	  $sql_pur_agt="SELECT * FROM book_order WHERE Book_status='$ses_Pur_agt'" ; 
//$sql_pur_agt="SELECT * FROM  unitcount u INNER JOIN book_order b ON u.Unit_id=b.Unit_id WHERE Book_status='$ses_Pur_agt'";
$result_pur_agt=mysql_query($sql_pur_agt);
$numrows=mysql_num_rows($result_pur_agt);
?>
      </p>
      <table width=780 align=center border=1 cellpadding=4 cellspacing=0>
        <tr bgcolor=#C0C0C0>
          <th width=41 align="center">เลือก</th>
          <th width=152>ชื่อหนังสือ</th>
          <th width=167>จำนวนที่สั่งซื้อ</th>
          <th width=295>หน่วยนับ</th>
          <th width=350>ราคา</th>
        </tr>
        <?

while($data_pur_agt=mysql_fetch_array($result_pur_agt)){
	?>
        <tr>
          <td align="center"><input type=checkbox name=inChk[] id=inChk[] value=<?=$data_pur_agt[Book_Oid];?>></td>
          <td align=center><a href=Receiver_detail.php?purid=<?=sprintf("%06d",$data_pur_agt[Order_id]);?>><strong><strong>
            <?=$data_pur_agt[Book_Oname];?>
          </strong></strong></a><a href=detail.php?purid=<?=sprintf("%06d",$data_pur_agt[Book_Oname]);?>></a> </td>
          <td align=center><font size="2"><font size="2"><font size="2">
            <?
		echo "<select name=item id=item>" ;
		for ($i=1; $i<=100; $i++) {
			echo "<option value=$i>$i</option>" ;
		}
		echo "</select>" ;		     

	?>
          </font></font></font></td>
          <td align=center><font size="2">
            <?php
$sql2 = "select * From Unitcount";
$result2 = mysql_query($sql2);
$Num_Rows2 = mysql_num_rows($result2);
$result2 = mysql_query($sql2);
echo "<select name=productstypecode id=productstypecode class=input>";
echo "<option value=0>เลือกหน่วยนับ";
While($row2= mysql_fetch_array($result2)){
$productstypecode  = $row2["Unit_id"];
$productstypename = $row2["Unit_name"];

?>
                      <option value="<? echo "$productstypecode"; ?>" onBlur="return chkForm();"><? echo "$productstypename"; ?>
                      <? 
   } 
   echo "</option></select>";
   ?>
            </option>
          </font><strong><strong> &nbsp;</strong></strong></td>
          <td align=center><strong><strong>
            <?=number_format ($data_pur_agt[Book_Oprice],2);?>
          </strong></strong></td>
        </tr>
        <?
}
?>

<?	@session_start() ;
	include("config.php") ;
	
	?>
       <?
	if(isset($Submit)){
  	if(!session_is_registered("ses_b_id")){
					$ses_b_id=array();
					} 
					
				if(isset($_POST[Submit])){
					for($i=0;$i<count($inChk);$i++){
					
					
						$chk_array=in_array($inChk[$i],$ses_b_id);
						
				if($chk_array==false && isset($inChk[$i])){
				
		$sql = "SELECT * FROM book_order WHERE Book_Oid='$inChk[$i]'" ;	
		$result = mysql_query($sql) ;
		$data = mysql_fetch_array($result) ;
		
		$ses_b_id[] = $data[Book_Oid] ;
		$ses_b_title[] = $data[Book_Oname] ;
		$ses_b_price[] = $data[Book_Oprice] ;
		$ses_item[] = $_POST[item];
		$ses_unit[] = $_POST[productstypecode];
		session_register("ses_b_id") ;
		session_register("ses_b_title") ;
		session_register("ses_b_price") ;
		session_register("ses_item") ;
		session_register("ses_unit") ;
	


		} } } }
  ?>