https://docs.mongodb.com/getting-started/shell/query/
Overview
You can use the find() method to issue a query to retrieve data from a collection in MongoDB.
All queries in MongoDB have the scope of a single collection.
Queries can return all documents in a collection or only the documents that match a specified filter or criteria.
You can specify the filter or criteria in a document and pass as a parameter to the find() method.
The find() method returns query results in a cursor, which is an iterable object that yields documents.
Prerequisites
The examples in this section use the restaurants collection in the test database.
For instructions on populating the collection with the sample dataset, see Import Example Dataset.
In the mongo shell connected to a running mongod instance, switch to the test database.
use test
Query for All Documents in a Collection
To return all documents in a collection, call the find() method without a criteria document.
For example, the following operation queries for all documents in the restaurants collection.
db.restaurants.find()
The result set contains all documents in the restaurants collection.
如果collection name是数字的，那么
db["713000007000"].find()