title: Display checkbox options based on dropdown value in php
body: <p>once i select a particular value in dropdown menu based on that corresponding checkbox values should display</p>
  
  <p>this is for getting dropdown values dynamically, based on this below i should get checkbox values</p>
  
  <pre><code>&lt;tr&gt;
          &lt;?php
          $sub=mysql_query("select * from subjects");
          $suboption='';
          while($row=  mysql_fetch_assoc($sub))
          {
              $suboption .='&lt;option value = '.$row['sub_id'].'&gt;'.$row['subname'].'&lt;/option&gt;';
          }
          ?&gt;
        &lt;td width="15%"&gt;Subject :&lt;/td&gt;
        &lt;td id="add_subject"&gt;&lt;div id="add_subject1"&gt;
            &lt;select name="subject" id="subject" onchange="subjectskills(this.value)"&gt;
                &lt;option value=""&gt;Select Subject&lt;/option&gt;
                &lt;?php echo $suboption; ?&gt;
            &lt;/select&gt;
            &lt;/div&gt;&lt;/td&gt;
      &lt;/tr&gt;
  </code></pre>