如何在mysql php中使用“Group By”獲得平均值

Question

我在mysql中使用“GroupBy”獲得“Average”

id      config_id       question    rating
1       68              lorem1      3
2       68              lorem2      5
3       69              lorem3      5
4       68              lorem1      NULL

我想獲得每個“config_id”的平均評分（不重復）我嘗試使用以下代碼，但對我不起作用

SELECT AVG(rating) AS AVERAGE 
FROM (SELECT config_id, AVG(rating) AS avg_rating 
      FROM "nps_ans" GROUP BY config_id) A
    ;
        

Answer 1

SELECT AVG(rating) AS AVERAGE
FROM nps_ans GROUP BY config_id;

Answer 2

如果您需要與問題無關的每個 config_id 的平均值，

select config_id,AVG(rating) AS average from nps_ans group by config_id;

要么

select question,config_id,AVG(rating) AS average from nps_ans group by config_id,question;

如果您需要每個配置和每個問題的平均評分。