query inside a while loop

Question

are/is there any problem with this code?

while($qtytoAdd > 0) {
    if(($remBalance - $qtytoAdd) >= 0) {
        mysql_query('UPDATE `estimates` SET `qty_rec` = `qty_rec` + "'.$qtytoAdd.'" WHERE `proj_id` = "'.$proj_id.'" AND `mat_id` = "'.mat_id_from_mat_desc($materials).'" AND `est_id` = "'.$balid.'"');
        mysql_query('UPDATE `requestdetails` SET `current_rec_qty` = `current_rec_qty` + "'.$qtytoAdd.'" WHERE `proj_id` = "'.$proj_id.'" AND `mat_id` = "'.mat_id_from_mat_desc($materials).'" AND `req_id` = "'.$currid.'"');
    } else {
        mysql_query('UPDATE `estimates` SET `qty_rec` = "'.$remBalance.'" + "'.$currRec.'" WHERE `proj_id` = "'.$proj_id.'" AND `mat_id` = "'.mat_id_from_mat_desc($materials).'" AND `est_id` = "'.$balid.'"');
        mysql_query('UPDATE `requestdetails` SET `current_rec_qty` = "'.$remBalance.'" + "'.$currRec.'" WHERE `proj_id` = "'.$proj_id.'" AND `mat_id` = "'.mat_id_from_mat_desc($materials).'" AND `req_id` = "'.$currid.'"');
        $qtytoAdd = $qtytoAdd - $remBalance;
    }
    return $qtytoAdd;
}

Both conditions seems to be working but the part where I'll assign the new values for $qtytoAdd is not. And do I need to use the return function to let it continue looping. I'm a newbie. Please help.

foreach($mat_desc as $mat_key => $materials){
    $qtytoAdd = $rec_qty[$mat_key];
    $remBalance = mysql_result(mysql_query('SELECT `est_qty` - `qty_rec` as balance FROM `estimates` WHERE `proj_id` = "'.$proj_id.'" AND `mat_id` = "'.mat_id_from_mat_desc($materials).'" AND `qty_rec` <> `est_qty` ORDER BY `item_id` ASC'), 0);
    $balid = mysql_result(mysql_query('SELECT `est_id` FROM `estimates` WHERE `proj_id` = "'.$proj_id.'" AND `mat_id` = "'.mat_id_from_mat_desc($materials).'" AND `qty_rec` <> `est_qty` ORDER BY `item_id` ASC'), 0);
    $currRec = mysql_result(mysql_query('SELECT `qty_rec` FROM `estimates` WHERE `proj_id` = "'.$proj_id.'" AND `mat_id` = "'.mat_id_from_mat_desc($materials).'" AND `qty_rec` <> `est_qty`'), 0);
    $currid = mysql_result(mysql_query('SELECT `req_id` FROM `requestdetails` JOIN `request` USING(`req_id`) WHERE `proj_id` = "'.$proj_id.'" AND `mat_id` = "'.mat_id_from_mat_desc($materials).'" AND `req_qty` <> `current_rec_qty` ORDER BY `req_id` ASC'), 0);

    mysql_query('INSERT INTO `receivedetails` (`rec_id`,`mat_id`,`rec_qty`) VALUES ('.$rec_id.','.mat_id_from_mat_desc($materials).','.$qtytoAdd.')');

    while($qtytoAdd > 0) {
        if(($remBalance - $qtytoAdd) >= 0) {
            mysql_query('UPDATE `estimates` SET `qty_rec` = `qty_rec` + "'.$qtytoAdd.'" WHERE `proj_id` = "'.$proj_id.'" AND `mat_id` = "'.mat_id_from_mat_desc($materials).'" AND `est_id` = "'.$balid.'"');
            mysql_query('UPDATE `requestdetails` SET `current_rec_qty` = `current_rec_qty` + "'.$qtytoAdd.'" WHERE `proj_id` = "'.$proj_id.'" AND `mat_id` = "'.mat_id_from_mat_desc($materials).'" AND `req_id` = "'.$currid.'"');
            $qtytoAdd = 0;
        } else {
            mysql_query('UPDATE `estimates` SET `qty_rec` = "'.$remBalance.'" + "'.$currRec.'" WHERE `proj_id` = "'.$proj_id.'" AND `mat_id` = "'.mat_id_from_mat_desc($materials).'" AND `est_id` = "'.$balid.'"');
            mysql_query('UPDATE `requestdetails` SET `current_rec_qty` = "'.$remBalance.'" + "'.$currRec.'" WHERE `proj_id` = "'.$proj_id.'" AND `mat_id` = "'.mat_id_from_mat_desc($materials).'" AND `req_id` = "'.$currid.'"');
            $qtytoAdd = $qtytoAdd - $remBalance;
        }
    }

    mysql_query('UPDATE `estimates` SET `qty_onhand` = `qty_rec` - `qty_rel` WHERE `proj_id` = '.$proj_id.' AND `qty_rec` <> `est_qty` AND `mat_id` = '.mat_id_from_mat_desc($materials).' AND `est_id` = '.$balid.'');
}

This is actually the whole code. :]

Answer 1

do I need to use the return function to let it continue looping

You don't need a return to continue to loop. You use return when you want to return from the current function and go back.

If called from within a function, the return statement immediately ends execution of the current function, and returns its argument as the value of the function call. return will also end the execution of an eval() statement or script file.

PHP & Query

while($qtytoAdd > 0) {
    if(($remBalance - $qtytoAdd) >= 0) {
        mysql_query('UPDATE `estimates` SET `qty_rec` = `qty_rec` + "'.$qtytoAdd.'" WHERE `proj_id` = "'.$proj_id.'" AND `mat_id` = "'.mat_id_from_mat_desc($materials).'" AND `est_id` = "'.$balid.'"');
        mysql_query('UPDATE `requestdetails` SET `current_rec_qty` = `current_rec_qty` + "'.$qtytoAdd.'" WHERE `proj_id` = "'.$proj_id.'" AND `mat_id` = "'.mat_id_from_mat_desc($materials).'" AND `req_id` = "'.$currid.'"');
        $qtytoAdd = $qtytoAdd - $remBalance; // this part does not exist in your code.
        ^^^^^^^^^^^^^^^^^^^^^^-------- depends on your requirement. I added the same line.  
 } else {
        mysql_query('UPDATE `estimates` SET `qty_rec` = "'.$remBalance.'" + "'.$currRec.'" WHERE `proj_id` = "'.$proj_id.'" AND `mat_id` = "'.mat_id_from_mat_desc($materials).'" AND `est_id` = "'.$balid.'"');
        mysql_query('UPDATE `requestdetails` SET `current_rec_qty` = "'.$remBalance.'" + "'.$currRec.'" WHERE `proj_id` = "'.$proj_id.'" AND `mat_id` = "'.mat_id_from_mat_desc($materials).'" AND `req_id` = "'.$currid.'"');
        $qtytoAdd = $qtytoAdd - $remBalance;
    }
}

Where you have gone wrong

According to your code if the 1st if is true you don't make changes to the $qtytoAdd. Plus you return from the function. So the while loop will be executed only once.