Re: Column value derived from generated column in INSERT?
От | Mark Raynsford |
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Тема | Re: Column value derived from generated column in INSERT? |
Дата | |
Msg-id | 20221019193057.39aff1c1@sunflower.int.arc7.info обсуждение исходный текст |
Ответ на | Re: Column value derived from generated column in INSERT? ("David G. Johnston" <david.g.johnston@gmail.com>) |
Ответы |
Re: Column value derived from generated column in INSERT?
Re: Column value derived from generated column in INSERT? |
Список | pgsql-general |
On 2022-10-19T11:58:07 -0700 "David G. Johnston" <david.g.johnston@gmail.com> wrote: > On Wed, Oct 19, 2022 at 10:36 AM Mark Raynsford <co+org.postgresql@io7m.com> > wrote: > > > insert into t (y) values (t.x * 2); > > > > I can think of various ways to do it with multiple statements, but a > > single statement would be preferable. > > > > > No, by extension of the documented constraint: "The generation expression > can refer to other columns in the table, but not other generated columns." > Hello! Just want to confirm that I wasn't misunderstood. The documentation in CREATE TABLE has the sentence you quoted above, and unless I'm misunderstanding that's saying that the expression used to generate values in GENERATED (ALWAYS AS) columns can't refer to other GENERATED columns. That's fine, but that's not what I was asking. In the table above, `x` is generated without references to other columns, but for the non-GENERATED `y` value, I want to refer to the value that `x` will have when I calculate a value for the `y` column in the INSERT statement. If that's not doable, that's fine, I just want to be sure. :) -- Mark Raynsford | https://www.io7m.com
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