SQL请求最大分组

Question

Hi guys Could you help me. Please find below images with input and output data So I need to code sql request to show only the maximum date in each competence_question_id, and also show a value of competence_answer_id with this date (I also have grouping by response_id but i hide it here)

Thank you in advance

SELECT response_id, competence_question_id, competence_answer_id, MAX(date_created)
FROM competence_vote_history
WHERE response_id = 53178
GROUP BY response_id, competence_question_id, competence_answer_id
ORDER BY response_id, competence_question_id

the table one with input data

the table two with output data

Answer 1

Try the following query for the desired result.

SELECT competence_question_id, competence_answer_id, date_created, answer_value
FROM competence_vote_history i
WHERE response_id = 53178 
    AND date_created = (
        SELECT MAX(date_created) 
        FROM competence_vote_history 
        WHERE response_id = i.response_id 
        AND competence_question_id = i.competence_question_id)
ORDER BY response_id, competence_question_id

Answer 2

If the date_created column doesn't have the date repeated, then you can use a derived table (where the max(date_created) is obtained for the competence_question_id) joined back to the original table:

SELECT V.*
  FROM (
         SELECT competence_question_id, MAX(date_created) AS MAXdate_created
           FROM competence_vote_history
          WHERE response_id = 53178
         GROUP BY competence_question_id
       ) AS dT INNER JOIN competence_vote_history V on dT.competence_question_id = V.competence_question_id
                                                   AND dT.MAXdate_created = V.date_created
ORDER BY response_id, competence_question_id