Hello ! Thank you for the good example and explanation !
Cheers ! > Sun Sep 13 2015 2:06:14 am CEST CEST from "James K. Lowden" ><jklowden at schemamania.org> Subject: Re: [sqlite] Third test of json and >index expressions, now it works > > On Wed, 09 Sep 2015 09:56:12 +0200 > "Domingo Alvarez Duarte" <sqlite-mail at dev.dadbiz.es> wrote: > > >>With your knowledge could you give your view about how evaluation of >> calculated/function columns should be done to have correct results. > .... > >>CREATE TABLE a(b); > .... > >>SELECT a, random() as r FROM a WHERE r <> r; >> > That's a syntax error, because there is no column a.r. > > Once you reorganize it to make it syntactically valid, the answer > becomes clear: > > select a, r from ( > SELECT a, random() as r FROM a > ) as R > WHERE r <> r; > > will yield zero rows, every time. Whatever value RANDOM produces goes > in the "r" column and any value, including "r", is always equal to > itself. > > --jkl > _______________________________________________ > sqlite-users mailing list > sqlite-users at mailinglists.sqlite.org > http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users > > > ?
