I use a modified form of option 3 with an ON UPDATE RULE.... the
update rule
copies the row to an inherited table...
CREATE TABLE dm_user (
id SERIAL NOT NULL PRIMARY KEY,
lu_user_type INTEGER NOT NULL REFERENCES lu_user_type(id),
dm_user_address INTEGER NOT NULL DEFAULT 0,
dm_user_email INTEGER NOT NULL DEFAULT 0,
f_name VARCHAR(50) NOT NULL,
m_name VARCHAR(50) NOT NULL,
l_name VARCHAR(50) NOT NULL,
uname VARCHAR(20) NOT NULL,
upwd VARCHAR(20) NOT NULL,
pwd_change_reqd BOOLEAN DEFAULT FALSE,
login_allowed BOOLEAN DEFAULT TRUE,
lost_passwd BOOLEAN DEFAULT FALSE,
create_dt TIMESTAMP NOT NULL DEFAULT NOW(),
change_dt TIMESTAMP NOT NULL DEFAULT NOW(),
change_id INTEGER NOT NULL DEFAULT 0,
active_flag BOOLEAN NOT NULL DEFAULT TRUE
) WITH OIDS;
CREATE TABLE dm_user_history (
history_id SERIAL NOT NULL PRIMARY KEY,
hist_create_dt TIMESTAMP NOT NULL DEFAULT NOW()
) INHERITS (dm_user);
CREATE RULE dm_user_upd_history AS ON UPDATE TO dm_user DO INSERT INTO
dm_user_history SELECT * FROM dm_user WHERE id = old.id;
CREATE RULE dm_user_nodelete AS ON DELETE TO dm_user DO INSTEAD UPDATE
dm_user SET active_flag = FALSE WHERE id = old.id;
"Scott Frankel" <leknarf@xxxxxxxxxxx> wrote in message
news:bd02bff5561d8b271301ba10bafca105@xxxxxxxxxxxxxx
Is there a canonical form that db schema designers use
to save changes to the data in their databases?
For example, given a table with rows of data, if I UPDATE
a field in a row, the previous value is lost. If I wanted to
track the changes to my data over time, it occurs to me that
I could,
1) copy the whole row of data using the new value, thus
leaving the old row intact in the db for fishing expeditions,
posterity, &c.
-- awfully wasteful, especially with binary data
2) enter a new row that contains only new data fields, requiring
building a full set of data through heavy lifting and multiple
queries
through 'n' number of old rows
-- overly complex query design probably leading to errors
3) create a new table that tracks changes
-- the table is either wide enough to mirror all columns in
the working table, or uses generic columns and API tricks to
parse token pair strings, ...
4) other?
Thanks
Scott
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