Выборка из базы по

<form action="test1.php" method="post">
    <div>Укажите тип позиции</div>
    <select name="item_type[]" size="7" multiple>
        <?php $select = pg_query($dbconn, "SELECT id, name FROM items_type WHERE deleted = 0");
        while ($option =pg_fetch_assoc($select)) :?>
        <option value="<?php echo $option['id'];?>"><?php echo $option['name'];?></option>
        <?php endwhile;?>
        </select>
    <div>Укажите призводителя</div>
    <select name="manufacturer[]" size="7" multiple>
        <?php $select = pg_query($dbconn, "SELECT id, name FROM manufacturer WHERE deleted = 0");
        while ($option =pg_fetch_assoc($select)) :?>
        <option value="<?php echo $option['id'];?>"><?php echo $option['name'];?></option>
        <?php endwhile; ?>
    </select>
    <input type="submit" value="ГО!">
</form>

if (!empty($_POST)) :
$where = 'WHERE ';
if (isset($_POST['item_type'])) {
$type = implode(",",$_POST['item_type']);
$where .= "id_type IN ($type) ";
}
if (isset($_POST['manufacturer'])) {
$manufacturer = implode(",",$_POST['manufacturer']);
$where .= "manufacturer_id IN ($manufacturer) ";
}
echo $where.'<br/>';
echo '<br/>';
$items = pg_query($dbconn, "SELECT id, name FROM stock_item $where");
$items = pg_fetch_all($items);
print_r($items);

if ((isset($_POST['item_type'])) && (isset($_POST['manufacturer'])))

function addWhere($where, $add, $and = true) {
    if ($where) {
      if ($and) $where .= " AND $add";
      else $where .= " OR $add";
    }
    else $where = $add;
    return $where;
}
if (!empty($_POST)) :
$where = "";
if (isset($_POST['item_type'])) $where = addWhere($where, "id_type IN (".htmlspecialchars(implode(",", $_POST["item_type"])).")");
if (isset($_POST['manufacturer'])) $where = addWhere($where, "manufacturer_id IN (".htmlspecialchars(implode(",", $_POST["manufacturer"])).")", false);
$sql = "SELECT id, name FROM stock_item";
if ($where) $sql .= " WHERE $where";
$items = pg_query($dbconn, $sql);
$items = pg_fetch_all($items);
print_r($items);