Date: Fri, 22 Apr 2005 03:58:52 +0200
From: Enrico Weigelt <weigelt@metux.de>
To: pgsql-sql <pgsql-sql@postgresql.org>
Subject: RULE for mtime recording
Message-ID: <20050422015852.GA1298@nibiru.borg.metux.de>
Reply-To: weigelt@metux.de
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Hi folks,


I'd like to write an update rule, which touches the a mtime field
(=current_timestamp) on normal update - when the mtime field isnt
explicitly set. If the update query explictly sets an mtime value,
this value has to be let through.

my tables look like:

    -- base class
    CREATE TABLE inode 
    (
	inode_id	oid not null default nextval('inode_id_seq'),
        mtime	timestamp not null default current_timestamp
    );

    -- example class
    CREATE TABLE foo
    (
	bar	text
    ) INHERITS ( inode );


now if I do 

    UPDATE foo SET bar = 'xyz' WHERE ...

the mtime should be set to the current time, but on 

    UPDATE foo SET bar = '123', mtime = '2001-09-11' WHERE ...

we shall have 9/11 as mtime.


Is this possible with rules ?


thx
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