its not working either way. Let me give you the steps I tried, may be there are some issues with my steps:
1) I have repeating section for a table item
2) It has one dropdown control which is bound to secondary Dataconnection (secondary DC is tied to a lookup table with the following column(id1, desc1, id2, desc2, id3, desc3)
3) the display name set to the desc3 column and value field is set to ID3 field
Now everything looks good as expected, now the requirement came to display Desc2 and Desc1
4) Now I created a rule on the Dropdown control
5) Action= Set a Field's value
6) set the Field= Desc2
5)@Desc2[@ID3[. = current()]]
I repeated the same for the Desc1
Now, when I preview and choose the dropdown first time it shows the expected value in Desc1 and Desc2. but when I choose another item, its not chaning the value. it still show the first selection data. -Any idea how to fix this?