Query: rds_db_subnet_groups_for_rds_db_instance

with rds_db_instance as (
  select
    arn,
    db_subnet_group_name,
    region,
    account_id
  from
    aws_rds_db_instance
  where
    account_id = split_part($1, ':', 5)
    and region = split_part($1, ':', 4)
    and arn = $1
  order by
    arn,
    db_subnet_group_name,
    region,
    account_id
), rds_db_subnet_group as (
  select
    arn,
    name,
    region,
    account_id
  from
    aws_rds_db_subnet_group
  where
    account_id = split_part($1, ':', 5)
    and region = split_part($1, ':', 4)
  order by
    arn,
    name,
    region,
    account_id
)
select
  g.arn as db_subnet_group_arn
from
  rds_db_instance as i,
  rds_db_subnet_group g
where
  i.db_subnet_group_name = g.name;