How can I use PHP to validate a drop down list
<p>I want to validate a form using PHP. Below is the sample of my form:</p>

<pre><code>&lt;form&gt;
    &lt;select name="select_box"&gt;
        &lt;option value="0"&gt;Please Select&lt;/option&gt;
        &lt;option value="1"&gt;OPT 1&lt;/option&gt;
        &lt;option value="2"&gt;OPT 2&lt;/option&gt;
    &lt;/select&gt;
    &lt;input type="submit" value="Go!" /&gt;
&lt;/form&gt;
</code></pre>
