输出3个查询

Question

得到这个3合1查询：

SELECT * FROM
(
SELECT mesures.date j, AVG(mesures.valeur) maxi 
FROM mesures
JOIN plages_horaire ON mesures.id_plage = plages_horaire.id_plage 
WHERE MONTH(mesures.date) = '9' AND YEAR(mesures.date) = '2016' AND mesures.code_station = 'P02SE' AND mesures.id_crit = '1' AND mesures.id_type = '1' 
GROUP BY mesures.date 
) maxi
,
(
SELECT AVG(mesures.valeur) mini
FROM mesures
JOIN plages_horaire ON mesures.id_plage = plages_horaire.id_plage 
WHERE MONTH(mesures.date) = '9' AND YEAR(mesures.date) = '2016' AND mesures.code_station = 'P02SE' AND mesures.id_crit = '1' AND mesures.id_type = '2' 
GROUP BY mesures.date
) mini
,
(
SELECT AVG(mesures.valeur) moy
FROM mesures
JOIN plages_horaire ON mesures.id_plage = plages_horaire.id_plage 
WHERE MONTH(mesures.date) = '9' AND YEAR(mesures.date) = '2016' AND mesures.code_station = 'P02SE' AND mesures.id_crit = '1' AND mesures.id_type = '3' 
GROUP BY mesures.date
) moy
GROUP BY j

问题是我得到了我想要的东西，除了最后两列的值在每一行都是相同的： query output

我相信它是因为GROUP BY。