Nested query for menu

Question

I have a table that has id, category_parent and
category_name. How can I write a query so that I can get nested
<ul> as follwing:
<ul id="nav">
<li> <a href="#" >first Level menu</a>
<ul>
<li><a href="#" >second Level
menu</a></li>
<li><a href="#" >second Level menu</a>
<ul>
<li><a href="#" >third Level
menu</a></li>
</ul>
</li>
</ul>
</li>
</ul>
Please help!!
-A

Answer 1

Hi,
I think Ken Ford's solution will work for 2 levels only.
We need to use recursive function. I made the sampe. It will work for n levels.
I used a static data for this example. I assumed first level menu contain parent id as 0.
My code:
<!---<cfquery name="request.menu" datasource="#dsn#">
  select id, category_parent, category_name from menu menuTable
</cfquery>--->
<cfscript>
  q = QueryNew('id,category_parent,category_name');
  newRow = QueryAddRow(q, 4);
  QuerySetCell(q, "id", "1", 1);
  QuerySetCell(q, "category_parent", "0", 1);
  QuerySetCell(q, "category_name", "First Level -1", 1);
  QuerySetCell(q, "id", "2", 2);
  QuerySetCell(q, "category_parent", "0", 2);
  QuerySetCell(q, "category_name", "First Level -2", 2);
  QuerySetCell(q, "id", "3", 3);
  QuerySetCell(q, "category_parent", "0", 3);
  QuerySetCell(q, "category_name", "First Level -3", 3);
  QuerySetCell(q, "id", "4", 4);
  QuerySetCell(q, "category_parent", "2", 4);
  QuerySetCell(q, "category_name", "second Level -1", 4);
  request.menu = q;
</cfscript>
<cffunction name="getChilds">
  <cfargument name="pId">
  <cfquery name="qChilds" dbtype="query">
      select * from request.menu
      where category_parent = <cfqueryparam value="#arguments.pId#" cfsqltype="cf_sql_bigint">
    </cfquery>
  <cfif qChilds.recordCount gt 0>
    <cfoutput query="qChilds">
      <ul>
        <li><a href="##">#category_name#</a></li>
        #getChilds(id)#
      </ul> 
    </cfoutput>
  <cfelse>
    <cfreturn>
  </cfif>
</cffunction>
<cfoutput>#getChilds(0)#</cfoutput>