CRUD

Figure 872. 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 873. 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 874. Deleting a document Slide presentation
Code Result 
db.group.deleteOne( {"_id": ObjectId(
   "5fa3035932b87a0c60a6ed1a")});
 
[
  {
    "acknowledged": true,
    "deletedCount": 1
  }
]

Figure 875. Deleting multiple documents Slide presentation
Code Result 
db.group.deleteMany({});
 
[
  {
    "acknowledged": true,
    "deletedCount": 23
  }
]

Figure 876. Multi valued attributes Slide presentation

Figure 877. Set semantics of multivalued attributes Slide presentation

Figure 878. Deleting selected attribute values Slide presentation

Figure 879. 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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