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I would like to create a rule that, by updating a view, allows me to
update
one table and insert into another.
The following example illustrates what I'm trying to do:
--Create Tables
CREATE TABLE my_table
(
my_table_id serial,
a character varying(255),
b character varying(255),
CONSTRAINT my_table_id_pk PRIMARY KEY (my_table_id)
);
CREATE TABLE my_audit_table
(
audit_id serial,
my_table_id int,
c character varying(255),
CONSTRAINT audit_id_pk PRIMARY KEY (audit_id)
);
--Create View
CREATE OR REPLACE VIEW my_view AS
SELECT
t.my_table_id,
t.a,
t.b,
au.audit_id,
au.c
FROM
my_table t, my_audit_table au
WHERE
t.my_table_id = au.my_table_id;
--Create Rules
CREATE OR REPLACE RULE insert_to_my_view AS
ON INSERT TO my_view
DO INSTEAD(
INSERT INTO my_table (a,b)
VALUES(new.a, new.b);
INSERT INTO my_audit_table(my_table_id, c)
VALUES
(currval('my_table_my_table_id_seq'), new.c);
);
CREATE OR REPLACE RULE update_my_view AS
ON UPDATE TO my_view DO INSTEAD
( UPDATE my_table SET
a = new.a,
b = new.b
WHERE
my_table_id = old.my_table_id;
INSERT INTO my_audit_table
(my_table_id,
c)
VALUES
(new.my_table_id,
new.c);
);
--The insert statement below inserts one row into my_table, and one row
into
my_audit_table
--(This works the way I would like)
insert into my_view(a,b,c) values('a contents','b contents', 'c
contents');
--The update statement below doesn't work the way I want.
--What I would like this to do is to update one row in my_table, and
insert
--one row into my_audit table. It does the update fine, but the insert to
my_audit_table
--doesn't work as I had anticipated.
update my_view set a = 'new a contents', b = 'new b contents', c = 'new c
contents' where my_table_id = 1;
-- If I execute the above update statement multiple times, multiple rows
will be
--inserted with each call after the first call.
--
--Specifically,
--after the first call, 1 row is inserted
--after the second call, 2 rows are inserted
--after the third call, 4 rows are inserted
--after the fourth call, 8 rows are inserted... and so on
--
--The problem is due to the INSERT in the update_my_view rule:
--
--INSERT INTO my_audit_table
-- (my_table_id,
-- c)
--VALUES
-- (new.my_table_id,
-- new.c);
--
--Apparently, "new.my_table_id" in this case references more than one row,
if more than one row with
--the given id already exists in my_audit_table.
--
--How do I accomplish what I want to accomplish here? I'd prefer not to
use
a sp.
Thanks,
Chad
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<div class=3DSection1>
<p class=3DMsoNormal>I would like to create a rule that, by updating a =
view,
allows me to update one table and insert into another.<o:p></o:p></p>
<p class=3DMsoNormal><o:p> </o:p></p>
<p class=3DMsoNormal>The following example illustrates what I’m =
trying to
do:<o:p></o:p></p>
<p class=3DMsoNormal><o:p> </o:p></p>
<p class=3DMsoNormal>--Create Tables<o:p></o:p></p>
<p class=3DMsoNormal>CREATE TABLE my_table <o:p></o:p></p>
<p class=3DMsoNormal>(<o:p></o:p></p>
<p =
class=3DMsoNormal> &=
nbsp; my_table_id
serial,<o:p></o:p></p>
<p =
class=3DMsoNormal> &=
nbsp; a
character varying(255),<o:p></o:p></p>
<p =
class=3DMsoNormal> &=
nbsp; b
character varying(255),<o:p></o:p></p>
<p class=3DMsoNormal>CONSTRAINT my_table_id_pk PRIMARY KEY =
(my_table_id)<o:p></o:p></p>
<p class=3DMsoNormal>);<o:p></o:p></p>
<p class=3DMsoNormal><o:p> </o:p></p>
<p class=3DMsoNormal>CREATE TABLE my_audit_table<o:p></o:p></p>
<p class=3DMsoNormal>(<o:p></o:p></p>
<p =
class=3DMsoNormal> &=
nbsp; audit_id
serial,<o:p></o:p></p>
<p =
class=3DMsoNormal> &=
nbsp; my_table_id
int,<o:p></o:p></p>
<p =
class=3DMsoNormal> &=
nbsp; c
character varying(255),<o:p></o:p></p>
<p class=3DMsoNormal>CONSTRAINT audit_id_pk PRIMARY KEY =
(audit_id)<o:p></o:p></p>
<p class=3DMsoNormal>);<o:p></o:p></p>
<p class=3DMsoNormal><o:p> </o:p></p>
<p class=3DMsoNormal>--Create View<o:p></o:p></p>
<p class=3DMsoNormal>CREATE OR REPLACE VIEW my_view AS<o:p></o:p></p>
<p class=3DMsoNormal>SELECT =
&=
nbsp; <o:p></o:p></p>
<p class=3DMsoNormal>t.my_table_id,<o:p></o:p></p>
<p class=3DMsoNormal>t.a,<o:p></o:p></p>
<p class=3DMsoNormal>t.b,<o:p></o:p></p>
<p class=3DMsoNormal>au.audit_id,<o:p></o:p></p>
<p class=3DMsoNormal>au.c<o:p></o:p></p>
<p class=3DMsoNormal>FROM<o:p></o:p></p>
<p =
class=3DMsoNormal> &=
nbsp; my_table
t, my_audit_table au<o:p></o:p></p>
<p class=3DMsoNormal>WHERE<o:p></o:p></p>
<p =
class=3DMsoNormal> &=
nbsp; t.my_table_id
=3D au.my_table_id;<o:p></o:p></p>
<p class=3DMsoNormal><o:p> </o:p></p>
<p class=3DMsoNormal>--Create Rules<o:p></o:p></p>
<p class=3DMsoNormal>CREATE OR REPLACE RULE insert_to_my_view AS =
<o:p></o:p></p>
<p class=3DMsoNormal>ON INSERT TO my_view <o:p></o:p></p>
<p class=3DMsoNormal>DO INSTEAD( <o:p></o:p></p>
<p class=3DMsoNormal>INSERT INTO my_table (a,b)<o:p></o:p></p>
<p class=3DMsoNormal>VALUES(new.a, new.b); <o:p></o:p></p>
<p class=3DMsoNormal>INSERT INTO my_audit_table(my_table_id, c) =
<o:p></o:p></p>
<p class=3DMsoNormal>VALUES <o:p></o:p></p>
<p class=3DMsoNormal>(currval('my_table_my_table_id_seq'), new.c); =
<o:p></o:p></p>
<p class=3DMsoNormal>);<o:p></o:p></p>
<p class=3DMsoNormal><o:p> </o:p></p>
<p class=3DMsoNormal>CREATE OR REPLACE RULE update_my_view AS =
<o:p></o:p></p>
<p class=3DMsoNormal>ON UPDATE TO my_view DO INSTEAD =
<o:p></o:p></p>
<p class=3DMsoNormal> ( UPDATE my_table SET <o:p></o:p></p>
<p =
class=3DMsoNormal> &=
nbsp; a
=3D new.a, <o:p></o:p></p>
<p =
class=3DMsoNormal> &=
nbsp; b
=3D new.b <o:p></o:p></p>
<p class=3DMsoNormal>WHERE <o:p></o:p></p>
<p =
class=3DMsoNormal> &=
nbsp; my_table_id
=3D old.my_table_id; <o:p></o:p></p>
<p class=3DMsoNormal>INSERT INTO my_audit_table <o:p></o:p></p>
<p =
class=3DMsoNormal> &=
nbsp; (my_table_id,
<o:p></o:p></p>
<p =
class=3DMsoNormal> &=
nbsp; c)
<o:p></o:p></p>
<p class=3DMsoNormal>VALUES <o:p></o:p></p>
<p =
class=3DMsoNormal> &=
nbsp; (new.my_table_id,
<o:p></o:p></p>
<p =
class=3DMsoNormal> &=
nbsp; new.c);
<o:p></o:p></p>
<p class=3DMsoNormal>);<o:p></o:p></p>
<p class=3DMsoNormal><o:p> </o:p></p>
<p class=3DMsoNormal>--The insert statement below inserts one row into =
my_table,
and one row into my_audit_table<o:p></o:p></p>
<p class=3DMsoNormal>--(This works the way I would like)<o:p></o:p></p>
<p class=3DMsoNormal>insert into my_view(a,b,c) values('a contents','b =
contents',
'c contents');<o:p></o:p></p>
<p class=3DMsoNormal><o:p> </o:p></p>
<p class=3DMsoNormal>--The update statement below doesn’t work the =
way I
want.<o:p></o:p></p>
<p class=3DMsoNormal>--What I would like this to do is to update one row =
in
my_table, and insert<o:p></o:p></p>
<p class=3DMsoNormal>--one row into my_audit table. It does the =
update
fine, but the insert to my_audit_table<o:p></o:p></p>
<p class=3DMsoNormal>--doesn't work as I had anticipated. =
<o:p></o:p></p>
<p class=3DMsoNormal>update my_view set a =3D 'new a contents', b =3D =
'new b
contents', c =3D 'new c contents' where my_table_id =3D =
1;<o:p></o:p></p>
<p class=3DMsoNormal><o:p> </o:p></p>
<p class=3DMsoNormal>-- If I execute the above update statement multiple =
times,
multiple rows will be <o:p></o:p></p>
<p class=3DMsoNormal>--inserted with each call after the first =
call.<o:p></o:p></p>
<p class=3DMsoNormal>--<o:p></o:p></p>
<p class=3DMsoNormal>--Specifically,<o:p></o:p></p>
<p class=3DMsoNormal>--after the first call, 1 row is =
inserted<o:p></o:p></p>
<p class=3DMsoNormal>--after the second call, 2 rows are =
inserted<o:p></o:p></p>
<p class=3DMsoNormal>--after the third call, 4 rows are =
inserted<o:p></o:p></p>
<p class=3DMsoNormal>--after the fourth call, 8 rows are inserted... and =
so on<o:p></o:p></p>
<p class=3DMsoNormal>--<o:p></o:p></p>
<p class=3DMsoNormal>--The problem is due to the INSERT in the =
update_my_view
rule:<o:p></o:p></p>
<p class=3DMsoNormal>--<o:p></o:p></p>
<p class=3DMsoNormal>--INSERT INTO my_audit_table <o:p></o:p></p>
<p =
class=3DMsoNormal>--  =
; =20
(my_table_id, <o:p></o:p></p>
<p =
class=3DMsoNormal>--  =
; =20
c) <o:p></o:p></p>
<p class=3DMsoNormal>--VALUES <o:p></o:p></p>
<p =
class=3DMsoNormal>--  =
; =20
(new.my_table_id, <o:p></o:p></p>
<p =
class=3DMsoNormal>--  =
; =20
new.c);<o:p></o:p></p>
<p class=3DMsoNormal>--<o:p></o:p></p>
<p class=3DMsoNormal>--Apparently, "new.my_table_id" in this =
case
references more than one row, if more than one row with <o:p></o:p></p>
<p class=3DMsoNormal>--the given id already exists in =
my_audit_table.<o:p></o:p></p>
<p class=3DMsoNormal>--<o:p></o:p></p>
<p class=3DMsoNormal>--How do I accomplish what I want to accomplish =
here?
I'd prefer not to use a sp.<o:p></o:p></p>
<p class=3DMsoNormal><o:p> </o:p></p>
<p class=3DMsoNormal>Thanks,<o:p></o:p></p>
<p class=3DMsoNormal>Chad<o:p></o:p></p>
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