mongodb嵌套查询子集合，如何过滤掉不符合条件的子集数据

### 回答1： 在 MongoDB 中，可以使用 $elemMatch 运算符来过滤嵌套在数组中的[[文档](https://geek.csdn.net/educolumn/3ff36b49b1643d1100a457ee835cde75?spm=1055.2569.3001.10083)](https://geek.csdn.net/edu/300981ef51993cfd737d329c71ba77f9?dp_token=eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJpZCI6NDQ0MDg2MiwiZXhwIjoxNzA3MzcxOTM4LCJpYXQiOjE3MDY3NjcxMzgsInVzZXJuYW1lIjoid2VpeGluXzY4NjQ1NjQ1In0.RrTYEnMNYPC7AQdoij4SBb0kKEgHoyvF-bZOG2eGQvc&spm=1055.2569.3001.10083)，具体用法如下： 例如，假设有一个[集合](https://geek.csdn.net/educolumn/ba94496e6cfa8630df5d047358ad9719?dp_token=eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJpZCI6NDQ0MDg2MiwiZXhwIjoxNzA3MzcxOTM4LCJpYXQiOjE3MDY3NjcxMzgsInVzZXJuYW1lIjoid2VpeGluXzY4NjQ1NjQ1In0.RrTYEnMNYPC7AQdoij4SBb0kKEgHoyvF-bZOG2eGQvc&spm=1055.2569.3001.10083) `students`，其中包含的[[文档](https://geek.csdn.net/educolumn/3ff36b49b1643d1100a457ee835cde75?spm=1055.2569.3001.10083)](https://geek.csdn.net/edu/300981ef51993cfd737d329c71ba77f9?dp_token=eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJpZCI6NDQ0MDg2MiwiZXhwIjoxNzA3MzcxOTM4LCJpYXQiOjE3MDY3NjcxMzgsInVzZXJuYW1lIjoid2VpeGluXzY4NjQ1NjQ1In0.RrTYEnMNYPC7AQdoij4SBb0kKEgHoyvF-bZOG2eGQvc&spm=1055.2569.3001.10083)如下： "_id": 1, "name": "张三", "scores": [ { "subject": "数学", "score": 80 }, { "subject": "语文", "score": 90 }, { "subject": "英语", "score": 70 } "_id": 2, "name": "李四", "scores": [ { "subject": "数学", "score": 60 }, { "subject": "语文", "score": 80 }, { "subject": "英语", "score": 90 } "_id": 3, "name": "王五", "scores": [ { "subject": "数学", "score": 90 }, { "subject": "语文", "score": 60 }, { "subject": "英语", "score": 80 } ```