- `show dbs` show all databases
- `use <db>` select a databse
- `show collections` list all the current db collections
- `db.<collection>.find()` query all the documents in current db collection
- `db.<collection>.count()` count all the documents in current db collection
- `db.dropDatabase()` delete current db
- `db.collection.deleteMany(...)` delete documents
- `db.collection.deleteOne(...)` delete a single document