php - Get variable isn't written to database -

i've got code

$cislonakupu=$_get['cislonakupu'];      if($_request['command']=='update'){         $datum = date("j/m/y h:i:s", time());     $user1=mysql_query("select * `register` `username`='$session'");     $mu=mysql_query("select * `velikostiobj` `objednavkac`='$cislonakupu'");$cislonakupu=$_get['cislonakupu'];          $customerid=mysql_insert_id();         $date=date('y-m-d');         $orderid=mysql_insert_id();          $max=count($_session['cart']);         for($i=0;$i<$max;$i++){             $pid=$_session['cart'][$i]['productid'];             $q=$_session['cart'][$i]['qty'];             $price=get_price($pid);             $cp=$_post['cp'];         $velikots=$row['velikost'];  $n= date('j/m/y h:i:s', strtotime($date. ' + 14 days'));      while ($row=mysql_fetch_array($mu)) {                          $resultik=mysql_query("insert `objednavkyinfo`(cislonakupu,produkt,mnozstvi,cena,cislofaktury,username,datumnakupu,dorucitdodata,velikost,dorucspol) values ('$cislonakupu','$pid','$q','$price','$cislofaktury','$session','$datum','$n','$velikots','$cp')") or die(mysql_error()); }          }         header("location: shoppingcart.php?delete=ano");       } 

i need write $velikots , database.

if $velikots="some text"; - it's working

if $velikots=$row['velikost']; - not working

where's problem?

you never fetch results. trying use results of query before fetch them database.

$row = mysql_fetch_assoc($mu); $velikots = $row['velikost']; 

you should able remove while loop:

 while ($row=mysql_fetch_array($mu)) { ... } // remove this. 

please, don't use mysql_* functions in new code. no longer maintained and officially deprecated. see red box? learn prepared statements instead, , use pdo or mysqli - this article decide which. if choose pdo, here tutorial. you wide open sql injections