PHP , PDO , Foreign Key -

i new php , doing project. question have:

in above interface, have extracted category name , id 'category name' combo box category table. , after form, should enter 'category id' 'item table', because category id foreign key of item table

this code have add

require_once '../../config/config.php';  $query = 'select `category_id`, `category_name` `tbl_category`';  $tbl_category_category_id = $query; $item_name = $_post['item_name']; $price = $_post['price']; $tbl_distributor_distributor_id= $_post['tbl_distributor_distributor_id']; $item_lowlevel = $_post['item_lowlevel']; $status = $_post['status'];      try {           $sql = "insert `tbl_item`(`tbl_category_category_id`, `item_name`, `price`, `tbl_distributor_distributor_id`, `item_lowlevel`,`status`)                values (:tbl_category_category_id, :item_name, :price, :tbl_distributor_distributor_id, :item_lowlevel ,:status)";         $qry = $conn->prepare($sql);         $qry->execute(array(':tbl_category_category_id' => $tbl_category_category_id,                             ':item_name' => $item_name,                             ':price' => $price,                             ':tbl_distributor_distributor_id' => $tbl_distributor_distributor_id,                             ':item_lowlevel' => $item_lowlevel,                             ':status' => $status));          $conn = null;     } catch (pdoexception $e) {         echo $e->getmessage();     } 

but master table of 'item table'. has added query. how correct this. how should take category id combo box , enter item table.

first need execute select statement

change this...

$query = 'select `category_id`, `category_name` `tbl_category`'; 

to this...

$sql = "select category_id, category_name tbl_category order category_name asc"; $query = $conn->prepare($sql); $query->execute(); $row = $query->fetch(pdo::fetch_assoc); 

next create select box using data select statement...

<select name="category_id" id="category_id"> <option value="">select category</option> <?php { ?>     <option value="<?php echo $row['category_id'] ?>"><?php echo $row['category_name'] ?></option> <?php } while ($row = $query->fetch(pdo::fetch_assoc)); ?> </select> 

finally category id
change this...

$tbl_category_category_id = $query; 

to this...

$tbl_category_category_id = $_post['category_id']; 

happy coding !