file1.php

<form action="file2.php" >
<select name='sgr'>
<option value='3'>test1</option>
<option value='4'>test2</option></select>

</td></tr>
</form>


file2.php

<?
<textarea><?php

switch( $sgr) {
case '3': echo 'aaaaaa'; break;
case '4': echo 'bbbbbb'; break;
}
?></textarea>

form을정해주고 값을 넘기면 받겠지만... submit하지않고 한페이지에서 출력하기 입니다. ㅠ
어떻게 방법이 다르게없을까여..

<form name=frms method=post action="" enctype="MULTIPART/FORM-DATA">
<select name='sgr' onchange="return co()">
<option value='3'>test1</option>
<option value='4'>test2</option>
</select>
<INPUT value="" maxLength=12 name=co1>
</form>

<script language='Javascript'>
var f = document.frms;

function co()
{
f.co1.value = f.sgr.value;
return;
}
</script>