CRUD

Figure 797. Adding a document Slide presentation
Code Result
db.group.insert(
    {
        cname: "All users",
        gid: "users",
    }
)
db.group.find()

[
  {
    "_id": {"$oid": "5fa3035932b87a0c60a6ed1a"},
    "cname": "New users",
    "gid": "users"
  }
]

Figure 798. Updating attributes Slide presentation
Code Result
db.group.update(
 {_id: ObjectId(
    "5fa3035932b87a0c60a6ed1a")},
 { $set:

     {
       cname: "New users" ,
       gidNumber: 1000 
     }
 }
)
db.group.find()

[
  {
    "_id": {"$oid": 
     "5fa3035932b87a0c60a6ed1a"},
    cname: "New users" ,
    "gid": "users",
    "gidNumber": 1000 
  }
]

Changing existing attribute value from "All Users" to "New Users".

Adding new attribute gidNumber with value 1000.


Figure 799. Deleting a document Slide presentation
Code Result
db.group.deleteOne( {"_id": ObjectId(
   "5fa3035932b87a0c60a6ed1a")});
[
  {
    "acknowledged": true,
    "deletedCount": 1
  }
]

Figure 800. Deleting multiple documents Slide presentation
Code Result
db.group.deleteMany({});
[
  {
    "acknowledged": true,
    "deletedCount": 23
  }
]

Figure 801. Multi valued attributes Slide presentation

Figure 802. Set semantics of multivalued attributes Slide presentation

Figure 803. Deleting selected attribute values Slide presentation

Figure 804. Deleting an attribute Slide presentation
Code Result
db.group.update(
    {_id: ObjectId(
    "5fa3035932b87a0c60a6ed1a")},

    { $unset:
            {
                gidNumber: 42 
            }
    }
)
db.group.find()

[
  {
    "_id": {"$oid": 
     "5fa3035932b87a0c60a6ed1a"},
    "cname": "My users",
    "gid": "users"
  }
]

Though the attribute is to be deleted the operation requires a dummy value for syntactical reasons.