>>>There are queries that cannot be formulated in first order predicate logic, and recursion is the single capability of SQL that exceeds FOPL power.
True, wrt SQLite and its dialect, for which RCTE provides Turing Completeness. Untrue for dialects of SQL that include PSM. >>>Unless the recursion is circular, I don't see how an SQL query over a finite database could fail to terminate. What does this mean? It is trivial to write a recursive CTE that does not terminate, and the property of "circularity" is not what makes the difference. Regards David M Bennett FACS Andl - A New Database Language - andl.org
