Re: [HACKERS] Re: [SQL] SQL-Query 2 get primary key

"D'Arcy J.M. Cain" wrote:
>
> Thus spake Marc Grimme
> > if I create a table like this:
> > CREATE TABLE test (
> > id decimal(3) primary key,
> > name varchar(32));
> >
> > how can I ask postgres which is the primary key from table test?
>
> SELECT pg_class.relname, pg_attribute.attname
> FROM pg_class, pg_attribute, pg_index
> WHERE pg_class.oid = pg_attribute.attrelid AND
> pg_class.oid = pg_index.indrelid AND
> pg_index.indkey[0] = pg_attribute.attnum AND
> pg_index.indisprimary = 't';

Should it work in 6.4.0 ?

It gives an empty table for me ;(

> That lists all the primary keys in your database. Add a "WHERE pg_class
> = 'test'" clause to get the specific table.

You probably mean "pg_class.relname = 'test'" ?

> Note that this makes the assumption that only one field can be in the
> primary key (no complex primary keys) but I don't think there will
> ever be more than one the way we declare it now.

Actually you can declare multi_field PK as
(Bruce: this probably should be added to \h create table):

hannu=> create table test(
hannu-> id1 int,
hannu-> id2 int,
hannu-> meat text,
hannu-> primary key (id1,id2)
hannu-> );
NOTICE: CREATE TABLE/PRIMARY KEY will create implicit index test_pkey
for table test
CREATE

-------------------------
Hannu