<?php
if (count($_POST["istek"]) == count($_POST["adet"])) {

    for ($i = 0; $i < count($_POST["istek"]); $i++) {
        $istek  = $_POST['istek'][$i];
        $adet   = $_POST['adet'][$i];
        $kaydet = $db->prepare("INSERT INTO istek_durum SET isd_istekid=:iid, isd_Hesapid=:hid, isd_hafta=:hft, isd_adet=:adt");
        $al     = $kaydet->execute(array(
            'iid' => $istek,
            'hid' => $Hid,
            'hft' => $hafta,
            'adt' => $adet
        ));
    }
}