文档
- https://www.mongodb.com/docs/manual/aggregation/
- 聚合查询的操作符 https://www.mongodb.com/docs/manual/reference/operator/aggregation/
聚合查询操作符的分类
常见的Mongo聚合操作和mysql的查询做对比
| SQL | Aggregate |
|---|---|
| where | $match |
| group by | $group |
| having | $match |
| select | $project |
| order by | $project |
| limit | $limit |
| sum() | $sum |
| count() | $sum |