Re: how to find primary key field name?

On 12/10/11 11:54, J.V. wrote:
> If I have a table name, I know how to find the primary key constraint
> name, but see no way to find the primary key field name.
>
> select constraint_name from information_schema.tabale_constraints
> where table_name = <table_name> and constraint_type = 'PRIMARY KEY';
>
> will return the constraint name, but given the table_name and the
> constraint_name, how do I find the database column/field name
> associated with that primary key?
>
> J.V.
>
You might find the following useful:

SELECT
cr.relname AS "Table",
ci.relname AS "Index",
a.attname AS "Primary Key Col"
FROM
pg_index i
JOIN pg_class cr ON (cr.oid = i.indrelid)
JOIN pg_namespace n ON (n.oid = cr.relnamespace)
JOIN pg_attribute a ON (a.attrelid = cr.oid)
JOIN pg_class ci ON (ci.oid = i.indexrelid)
WHERE
i.indisprimary AND
n.nspname = 'public' AND
EXISTS (SELECT 1 FROM unnest(i.indkey) p(c) WHERE p.c = a.attnum)
ORDER BY
cr.relname,
a.attname
/**/;/**/

Cheers,
Gavin