如何在SQL的相应列中选择不同值的计数？

Question

I have a table with 3 columns: first one is ID(not important here), second is number, and third is answer. The second and third column data is as follows:

number : answer
1      : yes
1      : yes
1      : no
2      : yes
2      : no
3      : yes
3      : no
3      : no

The output is supposed to be

number - total Yes - total No
1      -   2       -  1
2      -   1       -  1
3      -   1       -  2

ie the total number of yes and no for each number. Can someone guide me as to how to write this select query?

Answer 1

SELECT 
  number,
  COUNT(CASE WHEN answer = 'yes' THEN 1 END) AS total_yes,
  COUNT(CASE WHEN answer = 'no' THEN 1 END) AS total_no
FROM test_table
GROUP BY number

Here is a SQLFiddle

Answer 2

Assuming you are using sqlite then it will be as follows:

Select Cast(number as varchar) || ' - ' ||
Cast(Sum(case when answer = 'Yes' then 1 else 0 end) as varchar) || ' - ' || 
Cast(SUM(case when answer = 'No' then 1 else 0 end) as varchar)

from table

Group by number

For MySQL it will be:

Select CONCAT_WS(' - ', Cast(number as char),
Cast(Sum(case when answer = 'Yes' then 1 else 0 end) as char),
Cast(SUM(case when answer = 'No' then 1 else 0 end) as char))

from table

Group by number