RE: Foreign key constraints with constant values?
- From: "Bobak, Mark" <Mark.Bobak@xxxxxxxxxxxx>
- To: "orasnita@xxxxxxxxx" <orasnita@xxxxxxxxx>, "oracle-l@xxxxxxxxxxxxx" <oracle-l@xxxxxxxxxxxxx>
- Date: Sun, 24 Oct 2010 05:25:25 -0400
Hi Octavian,
I'm not sure I understand the intent in your second example below, however, if
you want to check a column value against a specific constant value (or list of
constant known values), you should use a CHECK constraint, rather than a
FOREIGN KEY constraint.
In general, if you have a static list of constant values, it may make more
sense to use a CHECK constraint. In the event of a dynamic, and possibly
changing list of valid values, it may make more sense to use a table and a
FOREIGN KEY constraint.
Hope that helps,
-Mark
________________________________________
From: oracle-l-bounce@xxxxxxxxxxxxx [oracle-l-bounce@xxxxxxxxxxxxx] On Behalf
Of Octavian Rasnita [orasnita@xxxxxxxxx]
Sent: Saturday, October 23, 2010 14:14
To: oracle-l@xxxxxxxxxxxxx
Subject: Foreign key constraints with constant values?
Hi,
I have made the following table:
create table client(
id integer not null,
name varchar2(200),
type1 integer not null,
type2 integer not null,
foreign key (type1, type2) references constants(id, type)
);
It works fine, but the column type2 contains a unique value in all the records.
Is it possible to drop that column and use the constant value from it in the
foreign key reference directly?
I have tried the following, but it gave an error:
create table client(
id integer not null,
name varchar2(200),
type1 integer not null,
foreign key (type1, 1) references constants(id, type)
);
Thanks.
Octavian
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