Query: rds_db_instance_in_vpc

select
  arn as resource,
  case
    when vpc_id is null then 'alarm'
    else 'ok'
  end as status,
  case
    when vpc_id is null then title || ' is not in VPC.'
    else title || ' is in VPC ' || vpc_id || '.'
  end as reason
  
  , region, account_id
from
  aws_rds_db_instance;