Re: views and rules

Michiel Lange <michiel@xxxxxxxxxxxxxx> writes:
> I cannot create rules on views

Sure you can.  Here's a trivial example.  This lets a user of view
"bar" see a subset of rows in "foo", update only some fields of
those rows, and not insert or delete anything:

regression=# create table foo (f1 int, f2 text);
CREATE TABLE
regression=# create view bar as select * from foo where f1 < 100;
CREATE VIEW
regression=# create rule bar_update as on update to bar do instead
regression-# update foo set f2 = new.f2 where f1 = old.f1;
CREATE RULE
regression=# insert into foo values(1,'ok');
INSERT 547779 1
regression=# insert into foo values(101, 'u cant see me');
INSERT 547780 1
regression=# select * from bar;
 f1 | f2
----+----
  1 | ok
(1 row)

regression=# update bar set f1 = f1+1, f2 = f2 || ' added';
UPDATE 1
regression=# select * from bar;
 f1 |    f2
----+----------
  1 | ok added
(1 row)

regression=# select * from foo;
 f1  |      f2
-----+---------------
 101 | u cant see me
   1 | ok added
(2 rows)


If you wanted to allow inserts or deletes via the view, you'd write
additional rules for that.

                        regards, tom lane

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