CRUD

Figure 812. 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 813. 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 814. Deleting a document Slide presentation
Code Result 
db.group.deleteOne( {"_id": ObjectId(
   "5fa3035932b87a0c60a6ed1a")});
 
[
  {
    "acknowledged": true,
    "deletedCount": 1
  }
]

Figure 815. Deleting multiple documents Slide presentation
Code Result 
db.group.deleteMany({});
 
[
  {
    "acknowledged": true,
    "deletedCount": 23
  }
]

Figure 816. Multi valued attributes Slide presentation

Figure 817. Set semantics of multivalued attributes Slide presentation

Figure 818. Deleting selected attribute values Slide presentation

Figure 819. 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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