distinct & count grouping distinct items?

Question

I'm trying to create one query to select some data. I need to select them only as DISTINCT but count each group of items inside each container eg

results: CATEGORY EMAIL

1. Jo1 user1@www.com
2. Jo1 user2@www.com
3. Jo1 user3@www.com
4. Jo2 user4@www.com
5. Jo2 user5@www.com

what I need: Jo1 3 -> count unique users Jo2 2 -> count unique users

I can do it with distinct to split them but can't find a way of counting separate groups. SELECT count(DISTINCT CATEGORY) ... counting all users.

Thnanks,

Answer 1

You should be COUNT(DISTINCT) ing email not category :

SELECT `CATEGORY`, COUNT(DISTINCT `EMAIL`)
FROM the_table
GROUP BY `CATEGORY`
;