Sorry, it was an error in previous letter. 3 липня 2009 р. 14:22 Віталій Тимчишин <tiv...@gmail.com> написав:
> > > 2009/7/1 Mike Ivanov <mi...@activestate.com> > >> >> >> > LEFT outer JOIN ville ON ville.uid = bien.ref_ville >> > LEFT outer JOIN freguesia_ville ON freguesia_ville.ref_ville =ville.uid >> >> This is not enough. You have to add this condition as well: >> >> AND bien.ref_ville = freguesia_ville.ref_ville >> >> In other words, when you link three tables by a common field, all three >> relationships should be explicitly expressed, otherwise you'll have this >> type of explosive row multiplication. >> > > Why so? Is not changing "freguesia_ville.ref_ville =ville.uid" to > "freguesia_ville.ref_ville =bien.ref_ville" enough (to prevent cases when > ville.uid is null as result of join)? > > >
