This tabular form prevents you from selecting more than 2 rows in the tabular form - as described here: https://forums.oracle.com/forums/thread.jspa?threadID=2524295&tstart=0

1. Give the tabular form a static ID. I called this one max2-tabular.
2. Figure out the name attribute of the check box. This is typically f01, but its worth double checking.
3. Create a new dynamic action:
   Event: Change
   Selection Type: jQuery selector
   jQuery Selector: #max2-tabular input[name="f01"]
   Condition: Javascript Expression
   Value: $('#max2-tabular input[name="f01"]:checked').size() > 2
4. True Action: Alert - just to give the user feedback that they can't select more than two rows.
5. True Action: Execute JavaScript code
   Code:

   
   event.stopPropagation();
   event.preventDefault();
   
   

6. Hide the check all checkbox by adding some css to the page. If you inspect the check-all checkbox, you can see it has an id of check-all-rows. So add the following css to the page attribute inline, to the css section:

   
   #max2-tabular #check-all-rows {
       visibility: hidden;
   }
   
   

7. It is important to update the dynamic action and specify the Event Scope as Dynamic, so that and additional rows that are added are still affected.