Creating a RULE for UPDATing a VIEW

From: "Dean Gibson (DB Administrator)" <postgresql(at)ultimeth(dot)com>
To: pgsql-sql(at)postgresql(dot)org
Subject: Creating a RULE for UPDATing a VIEW
Date: 2009-05-03 16:50:41
Message-ID: 49FDCB61.6020206@ultimeth.com
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Using PostgreSQL version 8.3.0:

For various reasons, I have a number of VIEWs that are (except for the
schema/table/view names) automatically generated as identity mappings of
corresponding TABLEs; eg:

CREATE VIEW public.yyy AS SELECT * FROM private.zzz;

Since we don't have updatable VIEWS yet, I tried:

CREATE RULE _update AS ON UPDATE TO public.yyy DO INSTEAD
UPDATE private.zzz SET (*) = NEW.* WHERE key_field = OLD.key_field;

In order to make the automatic generation easy, I'm trying to make the
syntax as general as possible, in particular, so that I don't have to
list all of the column names (that appears to work). However, the above
(and other ingenious, but also incorrect, syntaxes) produces an error
message. So, I tried:

CREATE RULE _update AS ON UPDATE TO public.yyy DO INSTEAD
(DELETE FROM private.zzz WHERE key_field = OLD.key_field;
INSERT INTO private.zzz VALUES( NEW.*) );

This is syntactically accepted, but when I attempt to UPDATE a row, the
old row is deleted but the new row is not inserted. Manually listing
the NEW.columns in place of "NEW.*" doesn't help.

-- Dean

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