CRUD

Figure 874. 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 875. Updating attributes Slide presentation
Code Result 
db.group.update(
 {_id: ObjectId(
    "5fa3035932b87a0c60a6ed1a")},
 { $set:

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

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

❶

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

❷

Adding new attribute gidNumber with value 1000.


Figure 876. Deleting a document Slide presentation
Code Result 
db.group.deleteOne( {"_id": ObjectId(
   "5fa3035932b87a0c60a6ed1a")});
 
[
  {
    "acknowledged": true,
    "deletedCount": 1
  }
]

Figure 877. Deleting multiple documents Slide presentation
Code Result 
db.group.deleteMany({});
 
[
  {
    "acknowledged": true,
    "deletedCount": 23
  }
]

Figure 878. Multi valued attributes Slide presentation

Figure 879. Set semantics of multivalued attributes Slide presentation

Figure 880. Deleting selected attribute values Slide presentation

Figure 881. Deleting an attribute Slide presentation
Code Result 
db.group.update(
    {_id: ObjectId(
    "5fa3035932b87a0c60a6ed1a")},

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

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

❶

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


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