On Fri, Sep 17, 2010 at 3:51 AM, Shawn Green (MySQL) < shawn.l.gr...@oracle.com> wrote:
> > So if 10 rows of A match your conditions, 1 row from B match your > conditions, and 10 rows from C match your conditions, then this query > produces 10*1*10 total row combinations. > Umm. It's friday, so I may be rather off it, too, but aren't the conditions inclusive ? They're AND, not OR. A Cartesian join on a(10 rows), b(1 row) and c(10 rows) would produce as you say. I would say that the number of rows is the number where * c.f3 is x, y or z * AND where b.f4 = yen * FROM the set produced by the join condition. Check the number of rows in c that match f3 in (x, y, z). Match those with rows in b as per join. This will yield the same or less rows. Filter those that match b.f4 = yen. This again will yield same or less. Match those with a as per join. This, too, will yield same or less, and will be your final number of rows. -- Bier met grenadyn Is als mosterd by den wyn Sy die't drinkt, is eene kwezel Hy die't drinkt, is ras een ezel
