Sorting with combobox

i need some help from you :)...when we select 'info' list in the combobox,automatically the article with type 'info' charateristic showed up, and when we select 'Berita' list in combobox,automatically the article with type 'Berita' charateristic showed up.. here is my code... it is a long script T.T & it use post method.. can you help me to make it a little bit simple? using function maybe. thanks before

<form method="post" name="form2">
  <select name="type" id="type">
    <option value="Semua">Semua</option>
    <option value="Berita">Berita</option>
    <option value="Info">Info</option>
  </select>
  <input type="submit" id="type" />
</form>

<table width="200" border="1" class="tbl_art_content" id="results">
<tbody>
  <tr>
  </tr>
    <?php
        $i=0;
        $no=0;
            if($_POST['type'] == 'Semua')
            {
                $query_art = mysql_query("SELECT * FROM artikel_tbl ORDER BY id") or die(mysql_error());
            }
            else if ($_POST['type'] == 'Berita')
            {
                $query_art = mysql_query("SELECT * FROM artikel_tbl WHERE type = 'Berita' ORDER BY id") or die(mysql_error());
            }
            else if ($_POST['type'] == 'Info')
            {
                $query_art = mysql_query("SELECT * FROM artikel_tbl WHERE type = 'Info' ORDER BY id") or die(mysql_error());
            }
            else
            {
                $query_art = mysql_query("SELECT * FROM artikel_tbl ORDER BY id") or die(mysql_error());
            }
            while($show=mysql_fetch_array($query_art))
            { 
                $no++;
                if(($no%2)==0)
                    $color = '#f2f2f2'; 
                else
                    $color = '#f9f9f9';
    ?>
  <tr bgcolor="<?php echo $color; ?>" class="rows">
    <td class="chk_content"><input type="checkbox" name="checked<?php echo $i; ?>" value="<?php echo $show['id']; ?>"/></td>
    <td class="no_content"><?php echo $no; ?></td>
    <td class="middle_content"><?php echo $show['judul']; ?></td>
    <td class="middle_content"><?php echo $show['penulis']; ?></td>
    <td class="middle_content"><?php echo $show['type']; ?></td>
    <td class="middle_content"><img src=".././upload/artikel/<?php echo $show['foto']; ?>" width="144" height="88"/></td>
    <td class="middle_content"><?php echo $show['tanggal']; ?></td>
    <td class="aksi_content"><div id="aksi_table">
            <ul>
                <li><a href="table_artikel.php?edit=<?php echo $show['id']; ?>"><img src="images/Apps-text-editor-icon.png" width="20" height="20" /></a></li>
                <li><a href="table_artikel.php?delete=<?php echo $show['id']; ?>" onclick="return confirm('Hapus artikel?')";><img src="images/Remove-icon.png" width="20" height="20"/></a></li>
            </ul>
        </div><!-- end of aksi_table --></td>
  </tr>
    <?php
        $i++; 
        }
    ?>
    <input type="hidden" name="n" value="<?php echo $i; ?>" /> 
    </tbody>
</table>