Re: Query for finding keys (IDs) that only have one of two values associated with it

[Peter Brawley]

select 
  post_id, 
  sum( if(meta_key='_VenueVenue',1,0)) as VenueVenues,
  sum( if(meta_key='_VenueLat',1,0) ) as VenueLats
from tbl
group by post_id
having VenueVenues>0 and VenueLats=0;

To suppress the 2nd & 3rd columns ...

select post_id 
from (
  select 
    post_id, 
    sum( if(meta_key='_VenueVenue',1,0)) as VenueVenues,
    sum( if(meta_key='_VenueLat',1,0) ) as VenueLats
  from tbl
  group by post_id
  having VenueVenues>0 and VenueLats=0
) x;