Mongodb is a very popular cross platform document-oriented, NoSQL(stands for “not only SQL”) database program, written in C++. It stores data in JSON format(as key-values pairs), which makes it easy to use. Mongdb can run over multiple servers, balancing the load to keep the system up and run in case of hardware failure.
Connecting to a Database
Step 1 – Establishing Connection: Port number Default: 27017
conn = MongoClient(‘localhost’, port-number)
If using default port-number i.e. 27017. Alternate connection method:
conn = MongoClient()
Step 2 – Create Database or Switch to Existing Database:
db = conn.dabasename
Create a collection or Switch to existing collection:
collection = db.collection_name
Deleting document from Collection or Database
In MongoDB, a single document can be deleted by the method delete_one(). The first parameter of the method would be a query object which defines the document to be deleted. If there is a reoccurrence of the same document, only the first appeared document would be deleted.
Note: Deleting a document is same as deleting a record in the case of SQL.
Consider the sample databse:
# Python program to demonstrate # delete_one import pymongo # creating Mongoclient object to # create database with the specified # connection URL students = pymongo.MongoClient('localhost', 27017) # connecting to a database with # name GFG Db = students["GFG"] # connecting to a collection with # name Geeks coll = Db["Geeks"] # creating query object myQuery ={'Class':'2'} coll.delete_one(myQuery) # print collection after deletion: for x in coll.find(): print(x) |
Output :
'_id': 2.0, 'Name': 'Golu', 'Class': '3'}
{'_id': 3.0, 'Name': 'Raja', 'Class': '4'}
{'_id': 4.0, 'Name': 'Moni', 'Class': '5'}
MongoDB Shell:
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