Selectbox for update value

Question

I have a selectbox in PHP, where the values and one value is selected. This selected value is data from table in MYSQL. Now, I need update/change this value to another which is in selectbox and send new value in table. When I send this new value from selectbox nothing happens. Can someone write how to update values ​​with selectbox.

  <?php echo "<form action=zap_azuriraj.php?y=".$_GET['y']."&b=".$_GET['b']."     method=POST>";
  echo $_GET['y'];
  $upit = "SELECT * FROM zapis WHERE zapis_id='$_GET[y]'";
    $rezultat = izvrsiUpit($upit);
    $rows = mysql_fetch_array($rezultat);

            $id_bilj=$rows['biljka_id'];
  $upit2 = "SELECT * FROM biljka";
    $rezultat1 = izvrsiUpit($upit2);
  if(isset($_GET['b'])) {


   echo"<select name='biljkaa_id'>"; }

   while ($row = mysql_fetch_array($rezultat1)){



  if ($row['biljka_id']==$id_bilj) {
   $optional="selected=\"selected\"";

 } 
  else { 
  $optional="";
    }
    echo "<option $optional value=".$row['biljka_id'].">".$row['naziv']."    </option>";
   }

   echo"</select>";

others are all working

 echo"<h3> Datum:</h3>";
echo"<input type=date name=date value=" . $rows[3] .     ">";
echo "<h3> Vrijeme:</h3>";
echo"<input type=time name=vrijeme value=" . $rows[4] .     ">";
echo"<h3>Opis:</h3>";
echo"<textarea name=opis >" . $rows[5] .     "</textarea>";
echo"<h3> Broj parcele:</h3>";
echo"<input type=text name=br_parcele value=" . $rows[6] .     ">";
echo"<h3> Broj biljke:</h3>";
echo"<input type=text name=br_biljke value=" . $rows[7] .     ">";


?>
<input type="submit" value="update" name="update">
</form>
<?php

I think the problem is in the commented line

       if(isset($_POST['update'])&&(isset($_POST['biljkaa_id']))){
   /* $biljka_id = $row['biljka_id'];*/
    $datum=$_POST['date'];
    $vrijeme = $_POST['vrijeme'];
    $opis = $_POST['opis'];
    $br_parcele = $_POST['br_parcele'];
    $br_biljke=$_POST['br_biljke'];
    $id=$_GET['y'];




  $upit="UPDATE zapis SET
            biljka_id='$biljka_id',
            datum='$datum',
            vrijeme='$vrijeme',
            opis='$opis',
            broj_parcele = '$br_parcele',
            broj_biljke = '$br_biljke'
            WHERE zapis_id='$id'"; 

    $rezultat = izvrsiUpit($upit);
    echo "Ažuriran je zapis";
  }
  ?>

Answer 1

I found a solution , thanks anyway

$biljka_id = $_POST['biljkaa_id'];