mongodb - mongo多个条件分组

Question

mongodb 有哪些 实现多个多个分组的？我知道mapreduce可以，还有吗？？

Answer 1

What is multiple condition grouping? ?
What are multiple multiple groups? ?

Answer 2

I have used this several times, I will post a code snippet for you to take a look

Answer 3

mongodb provides aggregation methods, of which $group should be able to achieve the grouping effect you want