Is there a simpler way to perform this query

Question

Here is that query (MySQL syntax):

select
  id_image
from
  (
    select
        id_image
      , count(id_image) as nb
    from
      data
    group by
      id_image
  ) temp_table
where
  nb = (select count(distinct id_group) from data)

• data is a table of 3 columns: int id_user, int id_group and int id_image
• A row (x, y, z) means that:
  • image z is in image group y
  • group y was created by user x

And we want to list all the images that are present in each image group. Thanks.

Answer 1

You are selecting all Image IDs that occur in data as often as there are distinct group IDs in that table? That seems strange.

Anyhow, the query can be re-written as:

select id_image
from data 
group by id_image
having count(*) = (select count(distinct id_group) from data);

Answer 2

How about try this:

select id_group, id_image from data where id_group in (select distinct id_group from data);