MongoDB

Schema (Collection: students)

[
  {
    "student_id": "S001",
    "name": "Santhosh",
    "age": 20,
    "department": "CSBS",
    "cgpa": 9.0,
    "year": 2
  },
  {
    "student_id": "S002",
    "name": "Ravi",
    "age": 21,
    "department": "CS",
    "cgpa": 8.5,
    "year": 3
  },
  {
    "student_id": "S003",
    "name": "Priya",
    "age": 19,
    "department": "ECE",
    "cgpa": 7.8,
    "year": 1
  },
  {
    "student_id": "S004",
    "name": "Kiran",
    "age": 22,
    "department": "CS",
    "cgpa": 6.9,
    "year": 4
  },
  {
    "student_id": "S005",
    "name": "Anita",
    "age": 20,
    "department": "MECH",
    "cgpa": 7.2,
    "year": 2
  }
]

** Read (Query)**

All Students with CGPA > 8

{ cgpa: { $gt: 8 } }

Students Belonging to the Computer Science Department:

{ department: "CS" }

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:[e-mail]/?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 < 7.5.

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

const uri = "mongodb+srv://William:[e-mail]/?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 < 7.5
    const deleteManyResult = await students.deleteMany({ cgpa: { $lt: 7.5 } });
    console.log("Deleted students with CGPA < 7.5 — deletedCount:", deleteManyResult.deletedCount);

    // 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();