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[MyrinNew]

Objective

To gain hands-on experience in performing CRUD (Create, Read, Update, Delete) operations in MongoDB using a simple college student schema.


Create (Insert)

Insert at least 5 student records into the students collection.






// Task — Create (Insert)
const { MongoClient } = require("mongodb");

// Atlas connection string
const uri = "mongodb+srv://William:4dwQ454VgRgDtNSO@assignment.jfmqse7.mongod b.net/?retryWrites=true&w=majority&appName=Assignment";

async function run() {
const client = new MongoClient(uri);

try {
await client.connect();
console.log("Connected to MongoDB Atlas");

const db = client.db("Assign6");
const students = db.collection("students");

// 5 student records
const studentData = [
{ student_id: "S001", name: "John", age: 20, department: "CSBS", year: 2, cgpa: 9.0 },
{ student_id: "S002", name: "Emma", age: 21, department: "ECE", year: 3, cgpa: 8.7 },
{ student_id: "S003", name: "Liam", age: 19, department: "MECH", year: 1, cgpa: 8.3 },
{ student_id: "S004", name: "Olivia", age: 22, department: "CSBS", year: 4, cgpa: 9.2 },
{ student_id: "S005", name: "Noah", age: 20, department: "EEE", year: 2, cgpa: 7.8 }
];

const result = await students.insertMany(studentData);
console.log(`Successfully inserted ${result.insertedCount} student documents!`);

} catch (err) {
console.error("Error:", err);
} finally {
await client.close();
console.log("Connection closed.");
}
}

run();






















Read (Query)

• Display all student records.
• Find all students with CGPA > 8.
• Find students belonging to the Computer Science department.

// Task 2️ Read (Query)
const { MongoClient } = require("mongodb");

// Atlas connection string
const uri = "mongodb+srv://William:4dwQ454VgRgDtNSO@assignment.jfmqse7.mongod b.net/?retryWrites=true&w=majority&appName=Assignment\n" ;

async function run() {
const client = new MongoClient(uri);

try {
await client.connect();
console.log("Connected to MongoDB Atlas");

const db = client.db("Assign6");
const students = db.collection("students");

// Display all student records
const allStudents = await students.find().toArray();
console.log("\nAll Students:");
console.table(allStudents.map(s => ({
student_id: s.student_id,
name: s.name,
age: s.age,
department: s.department,
year: s.year,
cgpa: s.cgpa
})));

// Find all students with CGPA > 8
const highCgpaStudents = await students.find({ cgpa: { $gt: 8 } }).toArray();
console.log("\nStudents with CGPA > 8:");
console.table(highCgpaStudents.map(s => ({
student_id: s.student_id,
name: s.name,
cgpa: s.cgpa
})));

// Find students belonging to Computer Science department
const csStudents = await students.find({ department: "CSE" }).toArray();
console.log("\nComputer Science Department Students:");
console.table(csStudents.map(s => ({
student_id: s.student_id,
name: s.name,
year: s.year,
cgpa: s.cgpa
})));

} catch (err) {
console.error("Error:", err);
} finally {
await client.close();
console.log("Connection closed.");
}
}

run();
















Update

• Update the CGPA of a specific student.
• Increase the year of study for all 3rd year students by 1.

// Task 3️ — Update
const { MongoClient } = require("mongodb");

// connection string
const uri = "mongodb+srv://William:4dwQ454VgRgDtNSO@assignment.jfmqse7.mongod b.net/?retryWrites=true&w=majority&appName=Assignment";

async function run() {
const client = new MongoClient(uri);

try {
await client.connect();
console.log("Connected to MongoDB Atlas");

const db = client.db("Assign6");
const students = db.collection("students");

// 1️ Update CGPA of a specific student (e.g., student_id = S002)
const updateCGPAResult = await students.updateOne(
{ student_id: "S002" }, // filter
{ $set: { cgpa: 9.0 } } // new CGPA
);
console.log(`Updated CGPA for S002 — modifiedCount: ${updateCGPAResult.modifiedCount}`);

// 2️ Increase year of all 3rd-year students by 1
const increaseYearResult = await students.updateMany(
{ year: 3 }, // filter
{ $inc: { year: 1 } } // increment year by 1
);
console.log(`Increased year for ${increaseYearResult.modifiedCount} student(s)`);

// Display updated collection
const updatedStudents = await students.find().toArray();
console.log("\nUpdated Students Collection:");
console.table(updatedStudents.map(s => ({
student_id: s.student_id,
name: s.name,
year: s.year,
cgpa: s.cgpa
})));

} catch (err) {
console.error("Error:", err);
} finally {
await client.close();
console.log("Connection closed.");
}
}

run();










Delete

• Delete one student record by student_id.
• Delete all students having CGPA

const { MongoClient } = require("mongodb");

const uri = "mongodb+srv://William:4dwQ454VgRgDtNSO@assignment.jfmqse7.mongod b.net/?retryWrites=true&w=majority&appName=Assignment";

async function run() {
const client = new MongoClient(uri);

try {
await client.connect();
console.log("Connected to MongoDB Atlas");

const db = client.db("Assign6");
const students = db.collection("students");

// Delete one student record by student_id (example: S004)
const deleteOneResult = await students.deleteOne({ student_id: "S004" });
console.log("Deleted student S004 — deletedCount:", deleteOneResult.deletedCount);

// Delete all students having CGPA const deleteManyResult = await students.deleteMany({ cgpa: { $lt: 7.5 } });
console.log("Deleted students with CGPA
// Display remaining collection
const remainingStudents = await students.find().toArray();
console.log("Remaining Students Collection:");
console.table(remainingStudents.map(s => ({
student_id: s.student_id,
name: s.name,
year: s.year,
cgpa: s.cgpa
})));

} catch (err) {
console.error("Error:", err);
} finally {
await client.close();
console.log("Connection closed.");
}
}

run();













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