Question

I have following query where I am fetching Question count for exams created by CreatorID 1001

SELECT count(Questions.question_id) QuestionCount 
    FROM Exams 
        LEFT JOIN Questions  
            ON Exams.exam_id = Questions.exam_id_fk 
    WHERE Exams.CreatorId='1001'

I know this is really stupid question but at some point its possible that there can be 10,000 users executing same query I just want to make sure about performace. So is there any othso er better way than this to do it ?

Thanks.

Answer 1

Provided you do not need the Exams where no questions have been defined, the following should be faster:

SELECT
  count(Questions.question_id) QuestionCount 
FROM Exams 
INNER JOIN Questions  
        ON Exams.exam_id = Questions.exam_id_fk 
WHERE Exams.CreatorId='1001'

Also make sure you have an index on the appropriate fields. Try using EXPLAIN on the query.