Re: [HACKERS] what standard say ...
От | Vadim B. Mikheev |
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Тема | Re: [HACKERS] what standard say ... |
Дата | |
Msg-id | 34DAC06A.C8E9729@sable.krasnoyarsk.su обсуждение исходный текст |
Ответ на | what standard say ... ("Vadim B. Mikheev" <vadim@sable.krasnoyarsk.su>) |
Список | pgsql-hackers |
Thomas G. Lockhart wrote: > > > vac=> select count(*) from test where exists (select t1.y from test t1 where t1.y = x); > > ^ > > Is this correlated subquery or not ? > > (Note, that I don't use x with t1. prefix here) > > With current parser this works as un-correlated subquery... > > >From "The SQL Standard", 3rd ed., Date and Darwen: > > "... each unqualified column name is _implicitly_ qualified by a range variable name > defined (explicitly or implicitly) in the nearest applicable FROM clause." (the emphasis > is from the book, not me) > > It goes on to recommend reading the standard for full understanding, but it is pretty > clear that your interpretation is correct; in the example above x is implicitly equivalent > to t1.x. Ok. Nice to know that we are correct here :) Vadim
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