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mongodb 有哪些 实现多个多个分组的？我知道mapreduce可以，还有吗？？
What is multiple condition grouping? ? What are multiple multiple groups? ?
I have used this several times, I will post a code snippet for you to take a look
mongodb provides aggregation methods, of which $group should be able to achieve the grouping effect you want
$group
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What is multiple condition grouping? ?
What are multiple multiple groups? ?
I have used this several times, I will post a code snippet for you to take a look
mongodb provides aggregation methods, of which
$groupshould be able to achieve the grouping effect you want