How to discover foreign keys (without pulling hair out)
От | Ian Morgan |
---|---|
Тема | How to discover foreign keys (without pulling hair out) |
Дата | |
Msg-id | Pine.LNX.4.44.0204230157280.17139-100000@light.webcon.net обсуждение исходный текст |
Список | pgsql-sql |
Given a particular table, I want to get a list of all the foreign keys and what they refer to, something like: local table | local field | foreign table | foreign field -------------+-------------+---------------+---------------companies | prime | contacts | contact_idcompanies | referer | contacts | contact_idcontacts | company_id | companies | company_id etc.. Here's as far as I've gotten: To find the foreign keys in the "companies" table, do: SELECT tgargs FROM pg_trigger WHERE tgrelid = (select oid from pg_class where relname='companies') AND tgfoid = (select oid from pg_procwhere proname='RI_FKey_check_ins') ; tgargs ----------------------------------------------------------------------------- co.pri-c\000companies\000contacts\000UNSPECIFIED\000prime\000contact_id\000 co.ref-c\000companies\000contacts\000UNSPECIFIED\000referer\000contact_id\000 (2 rows) These are the 6 args to the RI_FKey_check_ins function that is called in relation to foreign key checking. 1 = trigger name 2 = local table 3 = foreign table 4 = ? (what is this one?) 5 = local field 6 = foreign field With painstaking use of position(), octet_length(), and substring(), one can extract the appropriate fields. Here's just one: select substring( ( select substring( tgargs, ( position('\\000'::bytea in tgargs) + octet_length('\\000companies\\000'::bytea) ) ) from test limit 1 ) from 1 for ( select position('\\000'::bytea in ( select substring( tgargs, ( position('\\000'::bytea in tgargs) + octet_length('\\000companies\\000'::bytea) ) ) from test limit 1 ) ) ) - 1 ) as foreign_table; foreign_table ---------------contacts (1 row) Obviously, if there's an easier way, I'm all ears. BTW, I would like to avoid custom functions if at all possible. Regards, Ian Morgan -- -------------------------------------------------------------------Ian E. Morgan Vice President & C.O.O. Webcon,Inc.imorgan@webcon.net PGP: #2DA40D07 www.webcon.net * Customized Linux network solutions foryour business * -------------------------------------------------------------------
В списке pgsql-sql по дате отправления: