week 6

Week 6: NoSQL with MongoDB - 30 Snippets

This week covers MongoDB, PyMongo, and CRUD operations. Below are 30 Python snippets categorized into 3 topics (10 per topic).

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1️⃣ Introduction to MongoDB (10 Snippets)

1. Checking MongoDB Version

mongod --version

2. Starting MongoDB Service (Linux/macOS)

sudo systemctl start mongod

3. Listing All Databases

mongo --eval "show dbs"

4. Creating a New Database in Mongo Shell

use mydatabase

5. Creating a New Collection

db.createCollection("users")

6. Inserting a Document into a Collection

db.users.insertOne({ "name": "Alice", "age": 25 })

7. Inserting Multiple Documents

db.users.insertMany([
    { "name": "Bob", "age": 30 },
    { "name": "Charlie", "age": 22 }
])

8. Fetching All Documents

db.users.find().pretty()

9. Updating a Document

db.users.updateOne({ "name": "Alice" }, { $set: { "age": 26 } })

10. Deleting a Document

db.users.deleteOne({ "name": "Charlie" })

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2️⃣ Connecting MongoDB with Python (PyMongo) (10 Snippets)

11. Installing PyMongo

pip install pymongo

12. Connecting to MongoDB

from pymongo import MongoClient

client = MongoClient("mongodb://localhost:27017/")
print("Connected to MongoDB!")

13. Listing All Databases

print(client.list_database_names())

14. Selecting a Database

db = client["mydatabase"]
print("Database selected!")

15. Creating a Collection

collection = db["users"]
print("Collection created!")

16. Inserting One Document

doc = {"name": "Alice", "age": 25}
collection.insert_one(doc)
print("Document inserted!")

17. Inserting Multiple Documents

docs = [
    {"name": "Bob", "age": 30},
    {"name": "Charlie", "age": 22}
]
collection.insert_many(docs)
print("Documents inserted!")

18. Fetching One Document

user = collection.find_one()
print(user)

19. Fetching All Documents

for user in collection.find():
    print(user)

20. Closing MongoDB Connection

client.close()
print("MongoDB connection closed!")

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3️⃣ CRUD Operations in MongoDB (10 Snippets)

21. Filtering Documents

query = {"age": {"$gt": 25}}
for user in collection.find(query):
    print(user)

22. Using .find() with Projection

for user in collection.find({}, {"_id": 0, "name": 1}):
    print(user)

23. Sorting Documents

for user in collection.find().sort("age"):
    print(user)

24. Updating One Document

collection.update_one({"name": "Alice"}, {"$set": {"age": 26}})
print("Document updated!")

25. Updating Multiple Documents

collection.update_many({"age": {"$lt": 30}}, {"$set": {"status": "young"}})
print("Multiple documents updated!")

26. Deleting One Document

collection.delete_one({"name": "Charlie"})
print("Document deleted!")

27. Deleting Multiple Documents

collection.delete_many({"age": {"$lt": 25}})
print("Multiple documents deleted!")

28. Counting Documents

count = collection.count_documents({})
print(f"Total documents: {count}")

29. Dropping a Collection

collection.drop()
print("Collection dropped!")

30. Aggregation Query Example

pipeline = [{"$group": {"_id": "$status", "count": {"$sum": 1}}}]
for result in collection.aggregate(pipeline):
    print(result)

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🔥 Summary of Topics

✅ MongoDB Basics (10) - Databases, Collections, CRUD operations in shell. ✅ PyMongo (10) - Connecting, inserting, retrieving, and managing collections. ✅ CRUD with PyMongo (10) - Filtering, sorting, updating, deleting, and aggregating.

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