Question

Please help to make the request.

There are two tables, artist and album.
I want to select only those artists whose albums contains a picture.
That is, if the actor has 10 albums and only one of them has a picture or does not contain, i want to skip (only if all albums artist has pictures)

table artist:

artist_id
---------|
1        |
2        |

table albums:

artist_id | album_id | picture_id
---------------------------------
1         | 122...   | true 
1         | 123...   | false
2         | 124...   | true
2         | 125...   | true

So, I want to select only artist where artist_id=2 (because all the albums have pictures);

Answer 1

there are a lot of solutions for this, the first that comes to my mind is a very simple sub-select to exclude the artists that have an album without an image:

SELECT
  *
FROM
  artist a
WHERE
  artist_id NOT IN 
    (SELECT DISTINCT artist_id FROM album WHERE picture_id = false);

EDIT:
if you have stored artists without albums, these have to be excluded, too (take a look at the comments for explanation). in that case, you’ll have to add something like:

AND
  1 <= (SELECT COUNT(*) FROM album WHERE artist_id = a.artist_id)