Data Model: SQL, Sub-Queries & Multiple Data Sets
Explain how BI Publisher data models combine multiple queries, parameters, and linked sub-queries into a single structured XML output.
A single report often needs data from more than one query — a header query for invoice-level detail, a linked sub-query for line items, and perhaps a third independent query for a summary chart — and BI Publisher's Data Model editor is built specifically to compose these into one coherent XML tree. Interviewers ask about this to test whether a candidate understands data modeling for documents, which has different constraints than a typical reporting query.
It's like assembling a family tree document: one query fetches each family (the parent group), and for each family, a second query fetches its members (the nested child group) — the final document naturally shows members indented under their own family, not as one flat, unsorted list of names.