Re: Is NULLIF nullable?
От | Dean Gibson (DB Administrator) |
---|---|
Тема | Re: Is NULLIF nullable? |
Дата | |
Msg-id | 5.1.0.14.2.20041109211131.00a89d00@imaps.mailpen.net обсуждение исходный текст |
Ответ на | Is NULLIF nullable? ("Dean Gibson (DB Administrator)" <postgresql4@ultimeth.com>) |
Список | pgsql-sql |
You can ignore my question below, since I just put the field definition below in an SQL FUNCTION and marked it STRICT. -- Dean Dean Gibson (DB Administrator) wrote on 2004-11-09 19:29: >Recently I asked about why a field from the nullable side of an OUTER JOIN >was causing the JOIN to be inefficient, and was told that it was because >that field had a CASE statement as part of its definition, and that CASE >(and by extension COALESCE) were non-nullable constructs. > >Is NULLIF nullable, in that sense? > >Reason: I'd like to define a VIEW with a field definition thusly: > >'P.O. Box' || NULLIF( po_box, ' '::char ) AS ... > >And I would like the field thusly defined to be nullable. > >-- Dean
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