Je veux un coude main on php sure deux buton

<form name="form1" method="post" action="afficher_res_add.php">
 	<?php
        mysql_connect('localhost','root','');
        mysql_select_db('maroc_admin');
            $requet_theme="select * from theme";
			$execution_theme=mysql_query($requet_theme);
			$requet_min="select * from ministere";
			$execution_min=mysql_query($requet_min);
        
    ?>

  <p  align="center">Ajouter un procedure</p>
  <table width="601" border="0" align="center" >
    <tr>
      <td class="Style3">
          <div id="Style3">
            <p>Theme* :</p>
          </div>      </td>
      <td><label>
      <select name="lst_theme" id="list">
      <option value="-1">Faites votre choix</option>
        <?php while ($resulta_th=mysql_fetch_array($execution_theme)){?>
        <option value="<?php echo $resulta_th['code_theme'];?>"><?php echo $resulta_th['nom_theme'];?></option>
        <?php }?>
        </select> 
      </label></td>
      
     
	  <td><label>
       <input type="submit" onclick="javascript:document.myForm.action="add_min.php" value="action1"> 
    
      </label></td>
    </tr>
    <tr>
      <td class="Style3">
      	<div id="Style3">
          <p>procedure* :</p>
        </div>      </td>
      <td><label>
        <input name="txt_proc" type="text" id="txt_proc" size="45">
      </label></td>
    </tr>
    <tr>
      <td class="Style3"><div id="Style3">
      <p>Pieces* :</p>
      </div>      </td>
      <td><label>
      <textarea name="txt_ps" id="txt_ps" cols="45" rows="5"></textarea>
      </label></td>
    </tr>
    <tr>
      <td class="Style3"><div id="Style3">
        <p>Autorite* :</p>
      </div></td>
      <td><label>
        <textarea name="txt_aut" cols="45" rows="4" id="txt_aut"></textarea>
      </label></td>
    </tr>
    <tr>
      <td class="Style3">
          <div id="Style3">
          	<p>base juridique* :</p>
      </div>      </td>
      <td><label>
      <textarea name="txt_bj" cols="45" rows="4" id="txt_bj"></textarea>
      </label></td>
    </tr>
    <tr>
      <td class="Style3">
          <div id="Style3">
            <p>Ministere* :</p>
        </div>      </td>
      <td><label>
        <select name="lst_min" id="list" >
      <option value="-1">Faites votre choix</option>
        <?php while ($resulta_min=mysql_fetch_array($execution_min)){?>
        <option value="<?php echo $resulta_min['code_ministere'];?>"><?php echo $resulta_min['nom_ministere'];?></option>
        <?php }?>
        </select>
      </label></td>
      <td><label>
        <input type="submit" name="button4" id="button4" value="add min">
      </label></td>
    </tr>
    <tr>
      <td><label>
        <input type="submit" name="button2" id="button2" value="Valider">
        <div align="center"></div>
      </label></td>
      <td><label>
        <input type="submit" name="button3" id="button3" value="Envoyer">
        <div align="center"></div>
      </label></td>
    </tr>
  </table>
</form>