How to check and not select null values after using Fetch.xml

Hi.

I'm organizing forms, views and fields in MS CRM 2011 (UR5, Windows Server 2008 R2) for a Marina Company. And have a question about it.

To find the related boats' contact information, I used a dynamic search approach coded below;

function getContactInformation() {

    var relatedGrid = document.getElementById("contactInformationSubGrid");
    var lookupField = Xrm.Page.getAttribute("new_identitycode").getValue();

    if (relatedGrid == null || relatedGrid.readyState != "complete") {
        setTimeout('getContactInformation()', 2000);
        return;
    }

    var fetchXml = "<?xml version='1.0'?>";
        fetchXml += "<fetch version='1.0' output-format='xml-platform' mapping='logical' distinct='false'>";
        fetchXml += "<entity name='new_boatcard'>";
        fetchXml += "<attribute name='new_boatownerid' />";
        fetchXml += "<attribute name='new_captainid' />";
        fetchXml += "<attribute name='new_communicationid' />";
        fetchXml += "<attribute name='new_realownerid' />";
        fetchXml += "<attribute name='new_responsibleid' />";
        fetchXml += "<order attribute='new_boatownerid' descending='false' />";
        fetchXml += "<filter type='and'>";
        fetchXml += "<condition attribute='new_identitycode' operator='eq' value='"+lookupField+"'/>";
        fetchXml += "</filter>";
        fetchXml += "</entity>";
        fetchXml += "</fetch>";

    try {
        relatedGrid.control.setParameter("fetchXml", fetchXml);
        relatedGrid.control.refresh();
    }
    catch (e){
        relatedGrid.control.SetParameter("fetchXml", fetchXml);
        relatedGrid.control.Refresh();
    }
}

There's no problem right now. But here is the situation;

If these fields have NULL values stored in DB, the function coded above returns the NULL values too. And subGrid displays NULLs(which is normal)

<attribute name='new_boatownerid' /><attribute name='new_captainid' /><attribute name='new_communicationid' /><attribute name='new_realownerid' /><attribute name='new_responsibleid' />

If whole 5 values are NULL,  function returns an empty row displayed in subGrid(and when I click, I get an exception).

So, I want to check values if these 5 values are NULL, don't display the row. Is there any way to do this?

Thanks in advance.

Can