Hi,
the Query Unit doesn't have the query output elements on which you can apply a Visibility Condition. A way for obtaining your result, could be the customization of the unit template. In the Query Unit template you can define a condition which avoids the printing of the value for a specific output (e.g. the OID). For example:
....
<th class="header"></th>
[%for(queryOutput in queryOutputs){%]
[% if (queryOutput['name']!='OID'){%] // if the output is not OID I print the header
<th valign="top" class="header" nowrap="nowrap">
<wr:Label context="queryOutput"/>
</th>
[%}%]
[%}%]
....
....
<c:forEach var="current" varStatus="status" items="${<wr:UnitId/>.data}">
....
[%for(queryOutput in queryOutputs){%]
[% if(queryOutput['name']!='OID'){ %] // if the output is not OID I print the value
<td valign="top" class="value" nowrap="nowrap">
[%printQueryOutputValue(queryOutput)%]
[%}%]
...
[%}%]
</c:forEach>
This is a possible solution to hide the OID Query output in the page which shows the results.