not getting output in group by using linq query - linq

Question

My table is:
Student_answer_Master:
Stud_ans_id QuestionId OptionId iscorrect
1 25 1 1
2 26 1 0
3 27 2 1
4 27 3 1
5 27 4 1
6 28 1 1
8 29 1 0
9 29 2 1
10 29 3 1
(my options are single choice and multiple choice(checkbox)).
now what i want to get total count of only those question which are correct.
1-indicate correct
0-indicate incorrect.
i want output:3(for questionid 25,27,28)
this is my linq query:
var data = (from temp in context.Student_Answer_Master
where temp.isCorrect == '1'
group temp by temp.Question_Id into g
select new {g.Key}).Count();
but here count is coming 0.
can any one tell me what is wrong with my query???

Answer 1

Try this this should work.
var data = (from temp in s
group temp by temp.Question_Id into g
select new { questionid = g.Key, minIscorrect = g.Min(x => x.isCorrect) }).Where(y => y.minIscorrect != 0).Count();
There are 2 things that looks wrong to me in your Query.
comparing an int to a char temp.isCorrect == '1' if you make it temp.isCorrect == 1, you will still get 4 as the count because you are eliminating the row that has wrong answer for Question id 29.
once you get the group, you need to check if there are any wrong answers for the question
if yes eliminate that and then put a count