选择选项后显示结果

Question

如何创建一个只显示基于所选三个选项之一（C / E / W）的选项的SQL语句。目前，它只显示每一个结果。

另外，我如何做到这一点，一旦选择了C / E / W而不需要提交按钮，结果会降到下面？

任何帮助都将不胜感激。

<select id="combobox">
    <option value="Central" id="C">C</option>
    <option value="East" id="E">E</option>
    <option value="West" id="W">W</option>
</select>
</p>
</div>
<div>
<?php 
    $query = "SELECT * FROM ROOMS"; 
    $result = mysql_query($query);

    if ($result == FALSE) die ("could not execute statement $query<br />");

    echo "<table>";
        while($row = mysql_fetch_array($result)){
        echo "<tr><td>" . $row['roomCode'] . "</td><td>" . $row['Park'] . "</td><td>" . $row['Capacity'] . "</td><td>" . $row['Style'] . "</td><td>" . $row['dataProjector'] . "</td><td>" . $row['Whiteboard'] . "</td><td>" . $row['OHP'] . "</td><td>" . $row['wheelchairAccess'] . "</td><td>" . $row['lectureCapture'] . "</td></tr>";
    }

    echo "</table>";

    mysql_close();
?>