InfoPath Dev

Hi guys, I am a newbie in InfoPath development. So here's my scenario. Two of my tables in Main Datasource are designed like this:
  ITEMS Table: ItemID, CategoryID
  ORDERS Table: OrderID, ProjectID, ItemID, Quantity

And one of my table in Secondary DataSource has this structure:
  CATEGORIES Table: CategoryID, CategoryDescription

I was unable to add Category table to Main DataSource because there'll be an issue with the "Submit" action due to table relationships, that's why its on Secondary DataSource. My problem is in doing the filtering for the Orders table, I have to filter it using the CategoryDescription which is on Secondary Datasource. Thanks!

How does the Categories table relate to the Orders table? The CategoryID in the Items table?

Category table is not related to the Orders table, but to the Items table. :)

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