multiple buttons on a form

You check the post or get data from your form, using the name of the button:

<form action='' method='post'>
  <button type="submit" name="reset">Clear</button>
  <button type="submit" name="submit">Submit</button>
</form>

PHP (after submission):

if(isset($_POST['reset'])) { /* ...clear and reset stuff... */ }
else if(isset($_POST['submit']) { /* ...submit stuff... */ }

Alternatively, you have two buttons with the same name, which both submit your form, and if/else their values:

<form action='' method='post'>
  <button name="submit" value="0">Clear</button>
  <button name="submit" value="1">Submit</button>
  <button name="submit" value="2">Something Else</button>
</form>

PHP (after submission):

if($_POST['submit']==0)      { /* ...clear and reset stuff... */ }
else if($_POST['submit']==1) { /* ...submit stuff... */ }
else if($_POST['submit']==2) { /* ...do something else... */ }