Re: sql faq

* Thus wrote Dan Anderson (dan@mathjunkies.com): > On Wed, 2003-09-24 at 12:30, Jonatan Pugliese. wrote: > > select MaeSocio.* from MaeSocio > > LEFT JOIN MaeSeguro ON MaeSocio.NroSocio=MaeSeguro.NroSocio > > where MaeSeguro.NroSocio is null > > > > MaeSeguro.NroSocio is not null > > > > count(*) MaeSocio = 354000 > > count(*) MaeSeguro=108000 > > > > how i can retype this query? > > <Stab in the dark> > SELECT * FROM MaeSocio WHERE ((MaeSocio.NroSocio = MaeSeguro.NroSocio) > AND (NroSocio = NULL)); > SELECT * FROM MaeSeguro WHERE MaeSeguro.NroSocio = MaeSocio.NroSocio; > > Process the data from there. > > Oh, and index MaeSeguro.NroSocio. That will make finding NULL values > easier. I think. :-D Also defining MaeSeguro.NroSocio as not null will make things even faster with the index. Curt -- "I used to think I was indecisive, but now I'm not so sure."