How can all collections be queried in MongoDB?

In MongoDB, you can use the method db.getCollectionNames() to query all collections. Here are the steps to query all collections:

1. Open the MongoDB command line terminal or graphical user interface tool like MongoDB Compass.
2. Connect to the MongoDB database.
3. Retrieve the names of all collections in the database.

Additionally, if you are using MongoDB version 4.0 or higher, you can also use the following command to query all collections:

db.listCollections()

This will return a cursor object containing all collection information. You can use the toArray() method to convert the cursor object into an array for viewing the query results.

Note: If you have not created any collections, the query result will be an empty array.