Question

My question is: How to get different values in one sql query? I am trying this:

SELECT 
          q.id,
          q.question_title,
          SUM(op.option_value) AS total_votes,
          COUNT(op.option_value) AS number_votes,
          tab.comments 
FROM
          questions_options AS op 
          INNER JOIN questions AS q 
                    ON (q.id = op.q_id) 
          INNER JOIN 
                    (SELECT 
                              SUM(p.unseen) AS comments 
                    FROM
                              questions_options AS p) tab 
                    ON (q.id = tab.q_id) 
WHERE op.option_value > 0 
GROUP BY q.question_title 

This query is working perfectly, If i remove the middle “INNER JOIN” (i.e shows me the id, question title, sum of total votes rating, and the number of votes….

But I want to show unseen comments also, which is another field in that table and takes “1” for unseen (unread) comment…

So how can I do this by putting unseen comments number….any idea or suggestions…

Answer 1

I think Judge Mental is right.

You should SELECT the “q_id” field in your subquery to be able to make an inner join to “tab.q_id”.

-Explanation-

Your first INNER JOIN looks like this:

SELECT * FROM questions_options AS op INNER JOIN questions AS q ON (q.id = op.q_id)

..so basically the relation (and join) between your two tables is based on
questions.id and questions_options.q_id.

Well, it’s the same story for you subquery.

In your subquery you define a SELECT statement FROM “questions_options”,
which will only return the columns/fields you put after your SELECT.

(SELECT SUM(p.unseen) AS comments FROM questions_options AS p) tab

To be able to use any data from you subquery, you will have to SELECT the
questions_options.q_id field and make a join with the questions.id field already
in your main query.

(SELECT p.q_id, SUM(p.unseen) AS comments FROM questions_options AS p) tab
INNER JOIN (...subquery...) ON (q.id = tab.q_id)

So tab.q_id refers to the p.q_id you selected in your subquery.