Keeping lastly selected value from a dropdownlist after button click

Just like the title says i'm having difficulties in achieving it.

Here's my dropdownlist:

<?php
      $query = "SELECT data, rel_id FROM $tbl_rel_balansas INNER JOIN $tbl_balansas ON $tbl_rel_balansas.rel_id = $tbl_balansas.id WHERE $tbl_rel_balansas.member_id = '$_SESSION[id]' group by data";
      $result = mysql_query ($query);
      echo "<select name=data value=''>Data</option>";
      while($nt=mysql_fetch_array($result)){
        echo "<option value=$nt[data] name=\"blabla\">$nt[data]</option>";
      }
      echo "</select>";
?>

Here's the buttonclick:

<?php
      if(isset($_POST['Submit']))
      {
        $query = "SELECT SUM(suma), paskirtis FROM $tbl_rel_balansas INNER JOIN $tbl_balansas ON $tbl_rel_balansas.rel_id = $tbl_balansas.id WHERE $tbl_rel_balansas.member_id = '$_SESSION[id]'  AND data ='".$_POST['data']."' group by paskirtis";
        $result = mysql_query ($query);
        echo "<tr><td>Paskirtis:</td><td>Biudzetas:</td><td>Isleista:</td><td>Likutis:</td></tr>";
        while($nt=mysql_fetch_array($result)){
            if($nt['SUM(suma)'] != null){
            $suma = $nt['SUM(suma)'];
        }
            echo "<tr><td>$nt[paskirtis]</td>
            <td><input type=\"text\" name=\"isleista[]\" value=\"Skiriamų pinigų kiekis...\" method=\"post\"></td><td>".$suma." Lt</td><td>--</td></tr> <br>";
        }
      }
?>

After I press it, it retrieves the data I want from the date I've chosen from the drop down list and also reset whole drop down list showing the first value of the dates from sql database, not the one I selected. If an开发者_Go百科yone knows how to keep the selected value in the list any help is greatly appriciated!

---

Try this, you need to place select="selected" in the while loop. See below code how I placed the $selected

<?php
      $query = "SELECT data, rel_id FROM $tbl_rel_balansas INNER JOIN $tbl_balansas ON $tbl_rel_balansas.rel_id = $tbl_balansas.id WHERE $tbl_rel_balansas.member_id = '$_SESSION[id]' group by data";
      $result = mysql_query ($query);
      echo "<select name=data value=''>Data</option>";
      while($nt=mysql_fetch_array($result)){
        $selected = ($_POST['blabla'] == $nt[data])?'selected="selected"':NULL;
            echo "<option value=$nt[data] name=\"blabla\" $selected >$nt[data]</option>";
      }
      echo "</select>";
?>