Postgres: SQL to list table foreign keys

You can do this via the information_schema tables. For example:

SELECT
    tc.table_schema, 
    tc.constraint_name, 
    tc.table_name, 
    kcu.column_name, 
    ccu.table_schema AS foreign_table_schema,
    ccu.table_name AS foreign_table_name,
    ccu.column_name AS foreign_column_name 
FROM 
    information_schema.table_constraints AS tc 
    JOIN information_schema.key_column_usage AS kcu
      ON tc.constraint_name = kcu.constraint_name
      AND tc.table_schema = kcu.table_schema
    JOIN information_schema.constraint_column_usage AS ccu
      ON ccu.constraint_name = tc.constraint_name
      AND ccu.table_schema = tc.table_schema
WHERE tc.constraint_type = 'FOREIGN KEY' AND tc.table_name='mytable';

psql does this, and if you start psql with:

psql -E

it will show you exactly what query is executed. In the case of finding foreign keys, it's:

SELECT conname,
  pg_catalog.pg_get_constraintdef(r.oid, true) as condef
FROM pg_catalog.pg_constraint r
WHERE r.conrelid = '16485' AND r.contype = 'f' ORDER BY 1

In this case, 16485 is the oid of the table I'm looking at - you can get that one by just casting your tablename to regclass like:

WHERE r.conrelid = 'mytable'::regclass

Schema-qualify the table name if it's not unique (or the first in your search_path):

WHERE r.conrelid = 'myschema.mytable'::regclass

Issue \d+ tablename on PostgreSQL prompt, in addition to showing table column's data types it'll show the indexes and foreign keys.