MongoDB - Blog - dev.to + LinkedIn Post

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:[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");

        // 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:[e-mail]/?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:[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();