multiple select in one sql statement

Question

I have a table of survey answers, something like:

date     |  q1  | q2 |
12/12/10 | yes | no | 
12/13/10 | no  | no | 

and I would like to

Answer 1

The first query from spiny norman will give a result like that:

q1    q2    count(*)
no    yes   2
yes   no    1
yes   yes   1

Which only groups couples of distinct results. I assume you want to group the overall number of yes/no by question. In that case, you'd have to do something like that:

SELECT 'q1' as Question, s1.q1 as Answer, count(*) as Count
FROM survey s1
WHERE date>='2010-10-01' AND date<'2010-10-30'
GROUP BY q1
UNION
SELECT 'q2' as Question, q2 as Answer, count(*) as Count
FROM survey
WHERE date>='2010-10-01' AND date<'2010-10-30'
GROUP BY q2

Result:

Question Answer    Count
q1       no        2
q1       yes       2
q2       no        1
q2       yes       3

Answer 2

You could use:

select q1, q2, count(*)
from survey
group by q1, q2

Or, if you want to get those exact same results:

select count(case when q1 = 'Yes' then q1 else null end) as q1_yes,
       count(case when q1 = 'No' then q1 else null end) as q1_no,
       count(case when q2 = 'Yes' then q2 else null end) as q2_yes
from survey

Your implementation of "case" may vary, the important thing is you can set everything you don't want to null and it won't be counted by count() :)