postgres check for foreign key
SELECT r.table_name FROM information_schema.constraint_column_usage u INNER JOIN information_schema.referential_constraints fk ON u.constraint_catalog = fk.unique_constraint_catalog AND u.constraint_schema = fk.unique_constraint_schema AND u.constraint_name = fk.unique_constraint_name INNER JOIN information_schema.key_column_usage r ON r.constraint_catalog = fk.constraint_catalog AND r.constraint_schema = fk.constraint_schema AND r.constraint_name = fk.constraint_name WHERE u.column_name = 'id' AND u.table_catalog = 'db_name' AND u.table_schema = 'public' AND u.table_name = 'table_a'
