计算一个表中的不同行

Question

I have table t1 :

id|id_title|action

The data in table:

1|1|like
2|1|like
3|1|unlike
4|2|share
5|2|share

So I want to get next result from query:

id|count like|count unlike|count share

1|2|1|0
2|0|0|2

I try to use next query:

SELECT id_title, ( Select Count(id) From T1 WHERE action='like') As CountOfItems FROM T1 GROUP BY id_title

But it return count of first row always. What I must do? Or maybe I must changed structure of table?

Answer 1

Just use conditional aggregation.

select
id_title
,sum(case when action='like' then 1 else 0 end) As Count_Like
,sum(case when action='unlike' then 1 else 0 end) As Count_Unlike
,sum(case when action='share' then 1 else 0 end) As Count_Share
FROM T1 
GROUP BY id_title

Answer 2

SELECT id_title AS id, SUM(action='like') AS 'count like', 
SUM(action='unlike') AS 'count unlike', SUM(action='share') 
AS 'count share' FROM t1 GROUP BY id_title

Let me know if that worked for you.