no output display in dropdown list

Here's an even more fun way to do it. People often forget that echo will output a comma-separated list of arguments.

I put each argument on a separate line in this example just to illustrate the technique. It would not have to be done that way and might make more sense (be easier to understand) if formatted differently.

PHP Code:

<select name="staff" id="staff" required>
    <option value="">Select Staff</option>
    <?php while ($row_subject = mysql_fetch_array($query_subject))
    {
        echo "<option value='",
        $row_subject['deo_code'],
        "'",
        $this->input->post('staff') == $row_subject['deo_code'] ? ' selected' : NULL,
        $row_subject['deo_code'],
        "-",
        $row_subject['deo_name'],
        "</option>";
     }?>
</select>