Re: Help on query

[Peter Brawley]

One step at a time ...

1. These are the ip_address_id values that occur just once in ip_pool ...

select ip_address_id, count(*) N
from ip_pool
group by ip_address_id
having N=1;

2. Join that result to ip_addresses ...

select a.ip_address
from ip_addresses a
join( 
  select ip_address_id, count(*) N
  from ip_pool
  group by ip_address_id
  having N=1
) b on a.id = b.ip_address_id;