On Tue, 11 Dec 2007, Anthony Clayden wrote: > I agree with Henning that HAVING is a 'terrible hack', but then SQL > altogether is a terrible hack.
Somehow, yes. > As that paper points out, HAVING is unnecessary - it's just a filter on > the result set of group-by. Yep. > It's crucial that in Relational Algebra everything is a table. (See Codd's 12 > rules). The result of GROUP BY we might want to pass to another GROUP BY, or > JOIN to another table, etc -- or does Henning propose a hierarchy of sets of > sets ... Yes, why not? Works fine in Haskell. Ok, Haskell programs do not construct different query processing strategies and compare them at run-time, so the comparison between Haskell compilers and databases is not quite fair. > of tables, presumably with a hierarchy of HAVINGHAVING's? map (map (map (filter p))) and so on :-) _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
