1. CREATE (Insert Documents)
Insert one document:
db.collectionName.insertOne({
name: "Alice",
age: 25,
city: "New York"
});
Insert multiple documents:
db.collectionName.insertMany([
{ name: "Bob", age: 30, city: "Los Angeles" },
{ name: "Charlie", age: 28, city: "Chicago" }
]);
2. READ (Query Documents)
Find all documents:
db.collectionName.find();
Find documents with a condition:
db.collectionName.find({ age: { $gt: 25 } });
Find one document:
db.collectionName.findOne({ name: "Alice" });
Project specific fields:
db.collectionName.find(
{ age: { $gt: 25 } },
{ name: 1, city: 1, _id: 0 } // show only name and city
);
3. UPDATE (Modify Documents)
Update one document:
db.collectionName.updateOne(
{ name: "Alice" }, // filter
{ $set: { age: 26 } } // update
);
Update multiple documents:
db.collectionName.updateMany(
{ city: "Chicago" },
{ $set: { city: "San Francisco" } }
);
Increment a value:
db.collectionName.updateOne(
{ name: "Bob" },
{ $inc: { age: 1 } } // increases age by 1
);
4. DELETE (Remove Documents)
Delete one document:
db.collectionName.deleteOne({ name: "Alice" });
Delete multiple documents:
db.collectionName.deleteMany({ age: { $lt: 30 } });
5. ADDITIONAL OPERATORS (Useful in CRUD)
$gt – greater than$lt – less than$gte – greater than or equal$lte – less than or equal$ne – not equal$in – in array$nin – not in array
