Re: get referential values

On Wed, Jan 19, 2011 at 12:08 PM, Esmin Gracic <esmin(dot)gracic(at)gmail(dot)com> wrote:
> Knowing only tablename (schema_name.table_name) how to retrieve foreign keys
> and related values. (using pg_catalog is preferred). I developing framework
> for adobe flex (on php and postgresql).
> Already figured out how to get primary key, not null columns and column
> types, but kinda stuck here.
> I can post these queries, if someone needs (it would be nice to have these
> in wiki - where I've seen the query for primary key retrieval).
>
> I need following format:
>
> select .... 'schema_name.table_name'::regclass....
>
> no | fk_name| table_column_name | foreign_table_name | foreign_column_name
>
> no is used for composite foreign keys.

If you fire up psql with the -E argument, it will spit out all the SQL
it uses to figure out such things, such as when you enter "\d
tablename". For instance, in psql:

test=# \d parent
-- lots of queries displayed to find the table's OID (24584, in this case),
-- indexes, constraints, etc.

********* QUERY **********
SELECT conname,
pg_catalog.pg_get_constraintdef(r.oid, true) as condef
FROM pg_catalog.pg_constraint r
WHERE r.conrelid = '24584' AND r.contype = 'f' ORDER BY 1
**************************

-- etc.

You should be able to adapt those queries (particularly the one shown
above, though you might have to parse out the "condef" column) to suit
your needs.

Josh