Question

I have a table T like this :

ID | brand
2 | 100
2 | 300
2 | 300
1 | 100
1 | 200

I want to find which ID,brand combination occur more than 50% for an ID. For ex : here the result should come as

ID | brand
2 | 300

as (2,300) occurs 2 out of 3 times in ID 2. In ID1, both combinations are 50% times so no row for ID 1.
Now I approached it like this:
First I found count of each ID,brand combination :

(select id,brand,count(*) c from T group by id,brand) as F

Then I list all IDs which satisfy above mentioned criteria

select ID from F group by ID having max(c)/count(*) > 0.5

It works perfectly, but the problem is I can’t get corresponding brand because when in above query, I give

select ID, brand ...

Then it always gives first brand of the table.
Here is the sql fiddle

Answer 1

Here’s my first attemp.

SELECT ID, BRAND
FROM
(
  SELECT t.ID, t.BRAND, s.TotalCount, 
          COUNT(*) * 1.0 / s.TotalCount Percentage
  FROM   T
         INNER JOIN
        (
          SELECT ID, COUNT(*) totalCOunt
          FROM   T
          GROUP  BY ID
        ) s ON T.ID = s.ID
  GROUP  BY ID, BRAND
  HAVING (COUNT(*) * 1.0 / s.TotalCount) > 0.5
) r

• SQLFiddle Demo
• SQLFiddle Demo