Group by two fields, and having count() on first field - oracle

Question

I have a table that stored users play list, a video can be viewed by multiple users for multiple times.
A records goes like this:
videoid, userid, time
123, abc , 2013-09-11
It means user(abc) has watched video(123) on 2013-09-11
Now I want to find distinct users watched video list (no duplication), and only show the users that have watched more than two videos.
SELECT videoid, userid
FROM table_play_list
WHERE SOME CONDICTION
GROUP BY userid, videoid
The sql only select distinct users watchlist, I also want to filter users that have watched more than two different videos.
I know I have to google and read the documentation first, some said 'HAVING' could solve this, unfortunately, I could not make it.

Answer 1

If I understand correctly, you are looking for users who watched more than two different videos. You can do this by using count(distinct) with a partition by clause:
select userid, videoid
from (SELECT userid, videoid, count(distinct videoid) over (partition by userid) as cnt
FROM table_play_list
WHERE <ANY CONDITION>
) t
where cnt > 2;

Answer 2

Try like this,
SELECT userid, count(*)
FROM table_play_list
--WHERE SOME CONDITION
GROUP BY user_id
having count(*) >2;
Try this if you need to get the count based on userid and videoid(users who watch the same video more than two times).
SELECT userid, videoid, count(*)
FROM table_play_list
--WHERE SOME CONDITION
GROUP BY user_id, video_id
having count(*) >2;

Answer 3

This is probably best handled with analytics (window functions). Without analytics you will probably need a self-join.
SQL> WITH table_play_list AS (
2 SELECT 123 videoid, 'a' userid FROM dual UNION ALL
3 SELECT 125 videoid, 'a' userid FROM dual UNION ALL
4 SELECT 123 videoid, 'b' userid FROM dual UNION ALL
5 SELECT 123 videoid, 'b' userid FROM dual UNION ALL
6 SELECT 123 videoid, 'c' userid FROM dual
7 )
8 SELECT videoid, userid,
9 COUNT(*) over(PARTITION BY userid) nb_video
10 FROM table_play_list;
VIDEOID USERID NB_VIDEO
---------- ------ ----------
123 a 2
125 a 2
123 b 2
123 b 2
123 c 1
This lists all user/video and the total number of videos watched by each user. As you can see user b has watched the same video twice, I don't know if it's possible in your system.
You can filter with a subquery:
SQL> WITH table_play_list AS (
2 SELECT 123 videoid, 'a' userid FROM dual UNION ALL
3 SELECT 125 videoid, 'a' userid FROM dual UNION ALL
4 SELECT 123 videoid, 'b' userid FROM dual UNION ALL
5 SELECT 123 videoid, 'b' userid FROM dual UNION ALL
6 SELECT 123 videoid, 'c' userid FROM dual
7 )
8 SELECT *
9 FROM (SELECT videoid, userid,
10 COUNT(*) over(PARTITION BY userid) nb_video
11 FROM table_play_list)
12 WHERE nb_video > 1;
VIDEOID USERID NB_VIDEO
---------- ------ ----------
123 a 2
125 a 2
123 b 2
123 b 2

Answer 4

The below will give users who have watched more than two different videos.
SELECT userid, count(distinct video_id)
FROM table_play_list
WHERE SOME CONDICTION
GROUP BY user_id
having count(distinct video_id) >2;

Answer 5

If you use Oracle PL/SQL you can use like this:
SELECT column1, column2
FROM
(
SELECT column1, column2, COUNT(column1)
OVER (PARTITION BY column1) AS cnt
FROM test
GROUP BY column1, column2
ORDER BY column1
)
WHERE cnt > 2
If you use standard SQL you can use like this:
SELECT column1, column2
FROM test
WHERE column1 IN
(
SELECT column1
FROM
(
SELECT column1, column2
FROM test
GROUP BY column1, column2
ORDER BY column1
)
GROUP BY column1
HAVING COUNT(column1) > 2
)
GROUP BY column1, column2
ORDER BY column1