Re: Trigger for updating view with join

Heh, it's me spamming you again :)

now -- asking for comments.

> > create trigger fsl_update instead of insert or update on fsl ...
> >
> > but till now did not succeed in it. Quick googlink did not help either.
>
> Argh. My google-fu is definitely low in the night ;)
>
> for the record: it's right at
> http://www.postgresql.org/docs/9.1/static/plpgsql-trigger.html
> example 39-5

this example is only related, as the second one found at
http://vibhork.blogspot.ru/2011/10/updateable-views-in-postgresql-91-using.html
(the latter does not allow inserting one-to many records)

after a bit if try'n'error, I'm with the following

--- 8< ---
create table machines (
mid serial not null primary key,
mname text not null unique
);

create table fs (
fsid serial not null primary key,
mid int not null references machines,
mpoint text not null
);
create unique index fs_mp on fs(mid, mpoint);

create view fsl as
select fsid, mid, mname, mpoint
from fs join machines using(mid);

create or replace function update_fsl() returns trigger as $$
declare
mmid bigint;
begin
if (TG_OP = 'DELETE') then
-- only fs is deleted, not machine
delete from fs
where mpoint = OLD.mpoint and
mid = (select mid from machines where mname=OLD.mname);
if NOT FOUND then return NULL; else return OLD; end if;
elsif (TG_OP = 'INSERT') then
select mid into mmid from machines where mname=NEW.mname;
if NOT FOUND then
insert into machines (mname) values (NEW.mname);
select mid into mmid from machines where mname=NEW.mname;
end if;
insert into fs (mid, mpoint) select mmid, NEW.mpoint;
return NEW;
elsif (TG_OP = 'UPDATE') then
-- only mpoint is allowed to be changed
update fs set mpoint = NEW.mpoint
where mpoint = OLD.mpoint and
mid = (select mid from machines where mname=OLD.mname);
if NOT FOUND then return NULL; else return NEW; end if;
end if;
end;
$$ language plpgsql;
create trigger update_fsl instead of insert or update or delete on fsl for each row
execute procedure update_fsl();
--- 8< ---

I looks all requested operations are fine, but I'm a bit reluctant: maybe I
missed something easy but important?

Thanks!

--
Sincerely,
D.Marck [DM5020, MCK-RIPE, DM3-RIPN]
[ FreeBSD committer: marck(at)FreeBSD(dot)org ]
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*** Dmitry Morozovsky --- D.Marck --- Wild Woozle --- marck(at)rinet(dot)ru ***
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