Re: serial as FK ?

Oleg Bartunov wrote:
> Hi there,
> 
> what's wrong to use SERIAL as FK without explicit PRIMARY KEY or UNIQUE ?
> 
> qq=# create table t1( id serial);
> NOTICE:  CREATE TABLE will create implicit sequence "t1_id_seq" for 
> "serial" column "t1.id"
> CREATE TABLE
> qq=# create table t2( id2 int4 references t1(id));
> ERROR:  there is no unique constraint matching given keys for referenced 
> table "t1"
> 
> btw, Richard, I noticed this problem when looked into your example database
> http://www.archonet.com/pgdocs/chap-exdb.html#EXAMPLE-TABLES

Ah - IIRC there *was* nothing wrong with it when those notes were 
written (and I need to update them, clearly). Back then SERIAL implied 
UNIQUE too, but that was changed (in 7.3 I believe).

--   Richard Huxton  Archonet Ltd