Thread: reference to a view

In my db I have a table type_of_action, fields code varchar, name
varchar, medical boolean. Two other tables refer to this table, one of
them to the medical rows, the other one to the none-medical rows. I
would like to make the reference with a view, like this:

create table type of action_type (
  code varchar,
  name varchar,
  medical boolean
);

create view action_type_medical as select * from action_type
  where medical=true;
create view action_type_non_medical as select * from action_type
  where medical=false;

create table general_actions (
  field1, field2, field_etc,
  action_type varchar references action_type_non_medical(code)
);

create table medical_actions (
  field1, field2, field_etc,
  action_type varchar references action_type_medical(code)
);

But pg refuses this, can't create a reference to a view. I can now
create a trigger plus function that will do the check, but is there a
more elegant way? Thanks!

--
10:35-10:41
Fedora Core release 2 (Tettnang) Linux 2.6.6-1.435

On Wed, 16 Jun 2004, Joolz wrote:

> In my db I have a table type_of_action, fields code varchar, name
> varchar, medical boolean. Two other tables refer to this table, one of
> them to the medical rows, the other one to the none-medical rows. I
> would like to make the reference with a view, like this:
>
> create table type of action_type (
>   code varchar,
>   name varchar,
>   medical boolean
> );
>
> create view action_type_medical as select * from action_type
>   where medical=true;
> create view action_type_non_medical as select * from action_type
>   where medical=false;
>
> create table general_actions (
>   field1, field2, field_etc,
>   action_type varchar references action_type_non_medical(code)
> );
>
> create table medical_actions (
>   field1, field2, field_etc,
>   action_type varchar references action_type_medical(code)
> );
>
> But pg refuses this, can't create a reference to a view. I can now
> create a trigger plus function that will do the check, but is there a
> more elegant way? Thanks!

Not really right now.  Note, that to do foreign keys properly you need
triggers on action_type as well and those triggers need to take into
account the view conditions to determine what checks to do.

> [Stephan Szabo schreef op 16-06-2004 07:57 -0700]
>
> On Wed, 16 Jun 2004, Joolz wrote:
>
> > In my db I have a table type_of_action, fields code varchar, name
> > varchar, medical boolean. Two other tables refer to this table,
> > one of them to the medical rows, the other one to the none-medical
> > rows. I would like to make the reference with a view, like this:
> >
> > create table type of action_type (
> >   code varchar,
> >   name varchar,
> >   medical boolean
> > );
> >
> > create view action_type_medical as select * from action_type
> >   where medical=true;
> > create view action_type_non_medical as select * from action_type
> >   where medical=false;
> >
> > create table general_actions (
> >   field1, field2, field_etc,
> >   action_type varchar references action_type_non_medical(code)
> > );
> >
> > create table medical_actions (
> >   field1, field2, field_etc,
> >   action_type varchar references action_type_medical(code)
> > );
> >
> > But pg refuses this, can't create a reference to a view. I can now
> > create a trigger plus function that will do the check, but is
> > there a more elegant way? Thanks!
>
> Not really right now.  Note, that to do foreign keys properly you
> need triggers on action_type as well and those triggers need to take
> into account the view conditions to determine what checks to do.

Thanks for pointing that out. Considering this, it may be a better
idea after all to make two (physically) seperate tables after all.
After all, these are "only" domain tables, and I don't want the
reverse-update trigger to change any of my "real" data.

--
22:40-22:43
Fedora Core release 2 (Tettnang) Linux 2.6.6-1.435