Count unique ids on right table

Question

I have a mysql statement as follows:

SELECT * FROM class_members WHERE class_id = 1;

Which returns the following result:

class_id | user_id 1 | 2 1 | 1 1 | 3 1 | 5

I want to count all the unique user_ids per class.

Can anyone help?

Thank you

SELECT COUNT(DISTINCT user_id) FROM class_members WHERE class_id = 1; - done. — ɴᴀᴛᴇ ᴅᴇᴠ
– ɴᴀᴛᴇ ᴅᴇᴠ, Commented Jul 10, 2014 at 14:16

Quassnoi · Accepted Answer · 2014-07-10 14:16:42Z

4

SELECT class_id, COUNT(DISTINCT user_id) FROM mytable GROUP BY class_id

answered Jul 10, 2014 at 14:16

427k94 gold badges628 silver badges623 bronze badges

Sign up to request clarification or add additional context in comments.

1 Answer 1