How do I use two submit buttons, and differentiate between which one was used to submit the form? [duplicate]

Currently, I have an HTML form where the user will enter a title and text for an article. When it is time to submit, they are presented with two buttons. One is to 'save' their article without publishing it, and the other is to 'publish' the article and make it public.

I'm using PHP, and I am trying to figure out how to tell which button was used, in order to store the appropriate corresponding value in the database.

<td>
<input type="submit" class="noborder" id="save" value="" alt="Save" tabindex="4" />
</td>
<td>
<input type="submit" class="noborder" id="publish" value="" alt="Publish" tabindex="5" />
</td>

Probably should have mentioned this earlier, but I cannot assign the buttons values because the button is an image, so the text would show up above it.

Give each input a name attribute. Only the clicked input's name attribute will be sent to the server.

<input type="submit" name="publish" value="Publish">
<input type="submit" name="save" value="Save">

And then

<?php
    if (isset($_POST['publish'])) {
        # Publish-button was clicked
    }
    elseif (isset($_POST['save'])) {
        # Save-button was clicked
    }
?>

Edit: Changed value attributes to alt. Not sure this is the best approach for image buttons though, any particular reason you don't want to use input[type=image]?

Edit: Since this keeps getting upvotes I went ahead and changed the weird alt/value code to real submit inputs. I believe the original question asked for some sort of image buttons but there are so much better ways to achieve that nowadays instead of using input[type=image].

Give name and values to those submit buttons like:

    <td>
    <input type="submit" name='mybutton' class="noborder" id="save" value="save" alt="Save" tabindex="4" />
    </td>
    <td>
    <input type="submit" name='mybutton' class="noborder" id="publish" value="publish" alt="Publish" tabindex="5" />
    </td>

and then in your php script you could check

if($_POST['mybutton'] == 'save')
{
  ///do save processing
}
elseif($_POST['mybutton'] == 'publish')
{
  ///do publish processing here
}