mongodb练习题求大神帮帮忙

[weixin_41265746]

7.Find out the players with max era and min era per year
8.Find out the average, maximun and minimum h and er per team_id
9.Find out the average, maximun and minimum h and er per team_id and year
10.Order the team_id by the number of players in the team and group by year

需要加载CSV文件：https://pan.baidu.com/s/1slC39Ad
可以在这检测答案：http://104.131.155.18:8000/homework-4

[二月十六]

到mongodb版去问问 另外楼主可以先贴上自己写的的思路，然后哪里不懂再问，比直接给答案效果要好。