I'am wonder if someone could help me with my problem.

I created an xactionm definition, to fetch a list of clients from jndi defined for a MySQL DB.
This action would be used for the ServiceAction to make the list available to 3rd party apps via SOAP.

Now what I'am trying to do is to create a filter, so the results can be filtered by zip, product type,...
I have successfully created the action to take a zip parameter and to query the data accordingly.

My problems is, when a zip number is not passed, the query should igonore this parameter and return all results.
This is what I can't define so it would work.

This is my current xaction definition:
HTML Code:
<?xml version="1.0" encoding="UTF-8"?>
        <postnaStevilka type="string">
    <content type="content">
        <rule-result type="result-set"/>
          <postnaStevilka filter="none" style="text-box">
            <title>Select ZIP</title>
      <action-type>Filter param</action-type>
                <postnaStevilka type="string"/>
        <postnaStevilka type="string"/>  
        <query><![CDATA[SELECT * FROM ko_obcani WHERE N_PTT=CAST({postnaStevilka} AS UNSIGNED)]]></query>
        <!--<query-result type="result-set" mapping="query_result"/>-->
                <query-results type="result-set" mapping="rule-result"/> 
    <author>Report Designer</author>
    <help>Choose Report Output Format.</help>
Thanks for any help!