아래 거친마루님 께서 올리신 다중셀렉트에 비하면 허접입니다.
거친마루님께서 말씀하신대로 내용이 많은 Array형태의 무한다중셀렉트 입니다.
여기서 중요한것이 바로 무한 -_-; 한칸.두칸..세칸..짜리 셀렉트가 아닌 ...
붙이려면 계속 10칸 20칸도 가능합니다. 단, 내용이 많지 않을경우만요.....

<?
include " DB 연결 정보 ";
?>
<script>
<!--
var arrItems1 = new Array();
var arrItemsGrp1 = new Array();


<?php
$result=mysql_query("SELECT * FROM bigcate");
$i=1;
while($rows=mysql_fetch_array($result)){
$cont="$rows[bcate_name]";
printf("arrItems1[$i] = \"$cont\"; \n");
printf("arrItemsGrp1[$i] = $rows[bcate_id]; \n");
$i++;
}
?>

var arrItems2 = new Array();
var arrItemsGrp2 = new Array();

<?php
$result1=mysql_query("SELECT * FROM smallcate");
$i=1;
while($rows1=mysql_fetch_array($result1)){
$cont1="$rows1[scate_name]";
printf("arrItems2[$i] = \"$cont1\"; \n");
printf("arrItemsGrp2[$i] = $rows1[cid]; \n");
$i++;
}
?>

var arrItems3 = new Array();
var arrItemsGrp3 = new Array();

<?php
$result3=mysql_query("SELECT * FROM testcate");
$i=1;
while($rows3=mysql_fetch_array($result3)){
$cont3="$rows3[scate_name]";
printf("arrItems3[$i] = \"$cont3\"; \n");
printf("arrItemsGrp3[$i] = $rows3[cid]; \n");
$i++;
}
?>

function selectChange(control, controlToPopulate, ItemArray, GroupArray)
{
var myEle ;
var x ;
for (var q=controlToPopulate.options.length;q>=0;q--) controlToPopulate.options[q]=null;
if (control.name == "firstChoice") {
for (var q=myChoices.thirdChoice.options.length;q>=0;q--) myChoices.thirdChoice.options[q] = null;
}
myEle = document.createElement("option") ;
myEle.value = 0 ;
myEle.text = "[항목을 선택 하세요]" ;
controlToPopulate.add(myEle) ;
for ( x = 0 ; x < ItemArray.length ; x++ )
{
if ( GroupArray[x] == control.value )
{
myEle = document.createElement("option") ;
myEle.value = x ;
myEle.text = ItemArray[x] ;
controlToPopulate.add(myEle) ;
}
}
}
//-->
</script>

<form name='form' method='post' action='pds_upost.php' enctype='multipart/form-data'>
<SELECT id=aid name=acate onchange="selectChange(this, form.bid, arrItems1, arrItemsGrp1);">
<option value=0 SELECTED>[항목을 선택하세요]</option>
<option value=1 SELECTED>[자료실1]</option>
<option value=2 SELECTED>[자료실2]</option>
</select>

</SELECT>
<SELECT id=bid name=bcate onchange="selectChange(this, form.sid, arrItems2, arrItemsGrp2);"></SELECT>

<SELECT id=sid name=scate onchange="selectChange(this, form.cid, arrItems3, arrItemsGrp3);"></SELECT>

<SELECT id=cid name=ccate></SELECT>
</form>

아래 거친마루님 께서 올리신 다중셀렉트에 비하면 허접입니다. <br />
거친마루님께서 말씀하신대로 내용이 많은 Array형태의 무한다중셀렉트 입니다.<br />
여기서 중요한것이 바로 무한 -_-; 한칸.두칸..세칸..짜리 셀렉트가 아닌 ...<br />
붙이려면 계속 10칸 20칸도 가능합니다. 단, 내용이 많지 않을경우만요.....<br />
<br />
&lt;? <br />
include &quot; DB 연결 정보 &quot;;<br />
?&gt;<br />
&lt;script&gt;<br />
&lt;!--  <br />
var arrItems1 = new Array(); <br />
var arrItemsGrp1 = new Array();  <br />
 <br />
<br />
&lt;?php<br />
$result=mysql_query(&quot;SELECT * FROM bigcate&quot;);<br />
$i=1;<br />
while($rows=mysql_fetch_array($result)){<br />
$cont=&quot;$rows[bcate_name]&quot;;<br />
printf(&quot;arrItems1[$i] = \&quot;$cont\&quot;; \n&quot;);<br />
printf(&quot;arrItemsGrp1[$i] = $rows[bcate_id]; \n&quot;);<br />
$i++;<br />
}<br />
?&gt;<br />
<br />
var arrItems2 = new Array(); <br />
var arrItemsGrp2 = new Array(); <br />
<br />
&lt;?php<br />
$result1=mysql_query(&quot;SELECT * FROM smallcate&quot;);<br />
$i=1;<br />
while($rows1=mysql_fetch_array($result1)){<br />
$cont1=&quot;$rows1[scate_name]&quot;;<br />
printf(&quot;arrItems2[$i] = \&quot;$cont1\&quot;; \n&quot;);<br />
printf(&quot;arrItemsGrp2[$i] = $rows1[cid]; \n&quot;);<br />
$i++;<br />
}<br />
?&gt;<br />
<br />
var arrItems3 = new Array(); <br />
var arrItemsGrp3 = new Array(); <br />
<br />
&lt;?php<br />
$result3=mysql_query(&quot;SELECT * FROM testcate&quot;);<br />
$i=1;<br />
while($rows3=mysql_fetch_array($result3)){<br />
$cont3=&quot;$rows3[scate_name]&quot;;<br />
printf(&quot;arrItems3[$i] = \&quot;$cont3\&quot;; \n&quot;);<br />
printf(&quot;arrItemsGrp3[$i] = $rows3[cid]; \n&quot;);<br />
$i++;<br />
}<br />
?&gt;<br />
<br />
function selectChange(control, controlToPopulate, ItemArray, GroupArray)  <br />
{  <br />
  var myEle ;  <br />
  var x ;  <br />
  for (var q=controlToPopulate.options.length;q&gt;=0;q--) controlToPopulate.options[q]=null;  <br />
  if (control.name == &quot;firstChoice&quot;) {  <br />
    for (var q=myChoices.thirdChoice.options.length;q&gt;=0;q--) myChoices.thirdChoice.options[q] = null;  <br />
}  <br />
  myEle = document.createElement(&quot;option&quot;) ;  <br />
  myEle.value = 0 ;  <br />
  myEle.text = &quot;[항목을 선택 하세요]&quot; ;  <br />
  controlToPopulate.add(myEle) ;  <br />
  for ( x = 0 ; x &lt; ItemArray.length  ; x++ )  <br />
    {  <br />
      if ( GroupArray[x] == control.value )  <br />
        {  <br />
          myEle = document.createElement(&quot;option&quot;) ;  <br />
          myEle.value = x ;  <br />
          myEle.text = ItemArray[x] ;  <br />
          controlToPopulate.add(myEle) ;  <br />
        }  <br />
    }  <br />
}  <br />
//--&gt; <br />
&lt;/script&gt;<br />
<br />
&lt;form name=&#039;form&#039; method=&#039;post&#039; action=&#039;pds_upost.php&#039; enctype=&#039;multipart/form-data&#039;&gt;<br />
&lt;SELECT id=aid name=acate onchange=&quot;selectChange(this, form.bid, arrItems1, arrItemsGrp1);&quot;&gt;<br />
&lt;option value=0 SELECTED&gt;[항목을 선택하세요]&lt;/option&gt;<br />
&lt;option value=1 SELECTED&gt;[자료실1]&lt;/option&gt;<br />
&lt;option value=2 SELECTED&gt;[자료실2]&lt;/option&gt;<br />
&lt;/select&gt;<br />
<br />
&lt;/SELECT&gt;<br />
&lt;SELECT id=bid name=bcate onchange=&quot;selectChange(this, form.sid, arrItems2, arrItemsGrp2);&quot;&gt;&lt;/SELECT&gt;<br />
<br />
&lt;SELECT id=sid name=scate onchange=&quot;selectChange(this, form.cid, arrItems3, arrItemsGrp3);&quot;&gt;&lt;/SELECT&gt;<br />
<br />
&lt;SELECT id=cid name=ccate&gt;&lt;/SELECT&gt;<br />
&lt;/form&gt;