Question

I have following sql query in Rails 3 syntax:

    variab = Model.joins(:photo).where('photos.user_id = ?', user).group('model.photo_id').count

In the Models table I have these data:

+----+----------+----------+---------------------+----------+
| id | photo_id |  created_at          | updated_at         |
+----+----------+----------+---------------------+----------+
| 31 |      210 | 2011-09-16 14:38:22 | 2011-09-16 14:38:22 |
| 32 |      210 | 2011-09-16 14:38:22 | 2011-09-16 14:38:22 |
| 33 |      211 | 2011-09-16 15:03:26 | 2011-09-16 15:03:26 |
+----+----------+----------+---------------------+----------+

And I try to get the value 2 – I need to get count of unique photo_id data.
But if I will use the sql query above, so the output is ** 21022111** – I don’t understand, what this number mean… I would assume the output should be 2, but I don’t understand, why not…

If anyone could help me with this problem, I would be really glad… Thank you so much

Answer 1

Active Record is returning the photo_id/count pairs, i.e. photo_id 210 count 2, photo_id 211 count 1.

If you want to count the number of distinct photos for a given use then try:

Model.select(:photo_id).where(:user_id => user.id).count(:distinct => true)