Re: two primairy key in one table ?

On Thu, 4 Jul 2002, Angela Luyf wrote:

> Hello,
> I have a database model where a many to many relation is used, so i need
> to create a table with two primary key. Don't know how to solve this in
> postgress, can't find it in the tutorials, so can anybody help me with
> this ?

I always create a separate primary key field in the
intermediate table and do a unique index on the
other two fields.

p1.p1Id p2.p2Id
\ /
\ /
\ /
\ t3.t3Id /
t3.p1Id
t3.p2Id

besides of the normal primary and foreign keys I create
an unique index:

create unique index on t3 (p1Id, p2Id);

Regards Herbie
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Herbert Liechti http://www.thinx.ch
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