OCL25 — Introduce a "tuplejoin" operator

Author: Herman Balsters (h.balsters@bdk.rug.nl)
Description: OCL 2.0 is not as expressive as SQL (as opposed to common belief) and needs to be extended to this end
Rationale:
In my paper "Modeling Database Views with Derived Classes in the UML/OCL-framework" of this years UML conference (see proc. pp. 295-309) I investigated the issue of expressibility of OCL 2.0 w.r.t. to the query langauge SQL. I have demonstrated in that paper that OCL 2.0 is not as expressive as SQL (as opposed to common belief), and that OCL needs an additional "tuplejoin" operator to achieve the desired result.
If this issue cannot be dealt with in this phase, I propose it be retained and examined at the next stage.