ขอถามเรื่อง Search หน่อยครับ คือถ้าใน 1 หน้าเรามีการค้นหาหลายอย่างจะทำยังไงครับ ตามรูปนะครับ

<?php
<table border="0" width="600px" align="center">
	<tr><td class="txt4c" align="center"><strong>(ห้ามใช้คำย่อในการค้นหา)</strong></td></tr>
    <tr><td align="center"><input type="text" id="search" name="search1" /></td></tr>
<!-- ---------------------------------------------------------------------------------------------------------------------------- -->
	<tr>
    	<td align="center"><select name="search2" onChange="SelectCate('parent',this,0)">
			<option>ค้นหา1</option>
			<?
				$select = mysql_query("select * from traintype");
				while($row = mysql_fetch_array($select)) {
			?>
	  		<option value="<?=$row["Tra_Name"];?>"><? echo $row["Tra_Name"];?></option>
	  		<? } ?>
	  		</select></td>
  	</tr>
<!-- ---------------------------------------------------------------------------------------------------------------------------- -->
	<tr>
    	<td align="center"><select name="search3" onChange="SelectCate('parent',this,0)">
			<option>ค้นหา2</option>
			<?
				$select = mysql_query("select * from traintype2");
				while($row = mysql_fetch_array($select)) {
			?>
	  		<option value="<?=$row["TraTypeName"];?>"><? echo $row["TraTypeName"];?></option>
	  		<? } ?>
	  		</select></td>
  	</tr>
<!-- ---------------------------------------------------------------------------------------------------------------------------- -->
	<tr>
    	<td align="center"><select name="search4" onChange="SelectCate('parent',this,0)">
			<option>ค้นหา3</option>
			<?
				$select = mysql_query("select * from traintype2");
				while($row = mysql_fetch_array($select)) {
			?>
	  		<option value="<?=$row["TraTypeName"];?>"><? echo $row["TraTypeName"];?></option>
	  		<? } ?>
	  		</select></td>
  	</tr>
?>

<?php
if(isset($submitButton))
{
	if(isset($search1))
	{
	   statement or expression;
	}
	elseif(isset($search2))
	{
	   statement or expression;
	}
	elseif(isset($search3))
	{
	   statement or expression;
	}
	elseif(isset($search4))
	{
	   statement or expression;
	}
}
?>