Re: interval origami

Given the original:

CREATE TABLE Example (start REAL, stop REAL, tag TEXT);

I suppose it might make more sense to do it like this:

CREATE FUNCTION remove_bad(gs REAL, gf REAL, bs REAL, bf REAL)
   RETURNS SETOF Example AS $$
   BEGIN
      CASE
         WHEN ((bs <= gs) AND (bf <  gf)) THEN
            RETURN QUERY VALUES (bf, gf, 'interesting');
         WHEN ((bs >  gs) AND (bf <  gf)) THEN
            RETURN QUERY VALUES (gs, bs, 'interesting'),
               (bf, gf, 'interesting');
         WHEN ((bs >  gs) AND (bf >= gf)) THEN
            RETURN QUERY VALUES (gs, bs, 'interesting');
         WHEN ((bs <= gs) AND (bf >= gf)) THEN
            RETURN;
      END CASE;
   END; $$
LANGUAGE plpgsql;

SELECT remove_bad(10,40, 05,15);
SELECT remove_bad(10,40, 10,15);
SELECT remove_bad(10,40, 20,30);
SELECT remove_bad(10,40, 20,40);
SELECT remove_bad(10,40, 20,45);
SELECT remove_bad(10,40, 05,40);
SELECT remove_bad(10,40, 05,45);
SELECT remove_bad(10,40, 10,40);
SELECT remove_bad(10,40, 10,45);