CRUD

Figure 873. 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 874. 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 875. Deleting a document Slide presentation
Code Result 
db.group.deleteOne( {"_id": ObjectId(
   "5fa3035932b87a0c60a6ed1a")});
 
[
  {
    "acknowledged": true,
    "deletedCount": 1
  }
]

Figure 876. Deleting multiple documents Slide presentation
Code Result 
db.group.deleteMany({});
 
[
  {
    "acknowledged": true,
    "deletedCount": 23
  }
]

Figure 877. Multi valued attributes Slide presentation

Figure 878. Set semantics of multivalued attributes Slide presentation

Figure 879. Deleting selected attribute values Slide presentation

Figure 880. 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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