mongodb-tasks

Practice repository for MongoDB CRUD operations, including basic data types, nested objects, arrays, and upsert examples. Absolutely! I’ve taken your MongoDB tasks and formatted them neatly in Markdown with proper code blocks, explanations, and step-wise outputs. Here’s the complete representation:

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MongoDB Practice – Tasks Completed

TASK 1: Introductory Collection

Database: learning_mongo Collection: intro_test

1. Insert Documents

// Document with all basic data types
db.intro_test.insertOne({
    name: "Akshay",
    age: 20,
    isGraduate: true,
    date: Date(),
    subjects: ["Python", "HTML", "CSS"],
    Data: {},
    FailedSubjects: null
});

// Document with nested object
db.intro_test.insertOne({
    username: "akshay",
    age: 20,
    isGraduate: true,
    profile: {
        subjects: ["Python", "HTML", "CSS"],
        address: {
            room_no: 404,
            apartment_name: "ABC",
            street: "xyz",
            city: "Mumbai"
        }
    }
});

// Document with array of objects
db.intro_test.insertOne({
    name: "Rajesh",
    skills: [
        { skill: "Python", level: "Advanced" },
        { skill: "Data Analysis", level: "Intermediate" }
    ]
});

2. Retrieve All Documents

db.intro_test.find()

Output Example:

[
  {
    "_id": ObjectId("..."),
    "name": "Akshay",
    "age": 20,
    "isGraduate": true,
    "date": ISODate("2025-09-08T12:00:00Z"),
    "subjects": ["Python", "HTML", "CSS"],
    "Data": {},
    "FailedSubjects": null
  },
  {
    "_id": ObjectId("..."),
    "username": "akshay",
    "age": 20,
    "isGraduate": true,
    "profile": {
      "subjects": ["Python", "HTML", "CSS"],
      "address": {
        "room_no": 404,
        "apartment_name": "ABC",
        "street": "xyz",
        "city": "Mumbai"
      }
    }
  },
  {
    "_id": ObjectId("..."),
    "name": "Rajesh",
    "skills": [
      { "skill": "Python", "level": "Advanced" },
      { "skill": "Data Analysis", "level": "Intermediate" }
    ]
  }
]

---

TASK 2: CRUD Operations on students Collection

Database: learning_mongo Collection: students

---

1. Create (Insert Multiple Students)

db.students.insertMany([
  {
    name: "sahil",
    age: 19,
    city: "Pune",
    subjects: ["HTML", "CSS"],
    profile: { grade: "A", attendance: 95 }
  },
  {
    name: "Raj",
    age: 26,
    city: "Satara",
    subjects: ["Javascript", "Math"],
    profile: { grade: "A", attendance: 98 }
  },
  {
    name: "Suraj",
    age: 22,
    city: "Navi Mumbai",
    subjects: ["Python", "Bootstrap"],
    profile: { grade: "A", attendance: 93 }
  },
  {
    name: "Akshay",
    age: 20,
    city: "Saket",
    subjects: ["Python", "Math"],
    profile: { grade: "A", attendance: 96 }
  },
  {
    name: "Rajesh",
    age: 28,
    city: "Kolhapur",
    subjects: ["Python", "Go"],
    profile: { grade: "A", attendance: 95 }
  }
]);

Verify Insertion:

db.students.find()

---

2. Read (Query Students)

// All students
db.students.find()

// Students from "Navi Mumbai"
db.students.find({ city: "Navi Mumbai" })

// Students with age > 21
db.students.find({ age: { $gt: 21 } })

// Students having "Python" as a subject
db.students.find({ subjects: { $in: ["Python"] } })

// Show only name and city (hide _id)
db.students.find({}, { name: 1, city: 1, _id: 0 })

---

3. Update (Modify Data)

// Update Akshay's city to "Delhi"
db.students.updateOne({ name: "Akshay" }, { $set: { city: "Delhi" } })

// Increase all students' age by 1
db.students.updateMany({}, { $inc: { age: 1 } })

// Add new subject "MongoDB" to Rajesh's subjects
db.students.updateOne({ name: "Rajesh" }, { $push: { subjects: "MongoDB" } })

// Replace Rajesh's profile entirely
db.students.updateOne(
  { name: "Rajesh" },
  { $set: { profile: { grade: "C", attendance: 45 } } }
)

Check Updated Data:

db.students.find()

---

4. Delete (Remove Data)

// Delete student with city "Delhi"
db.students.deleteOne({ city: "Delhi" })

// Delete all students with age < 22
db.students.deleteMany({ age: { $lt: 22 } })

Verify Deletions:

db.students.find()

---

5. Upsert Operation

db.students.updateOne(
  { name: "Ravi" },
  { $set: { name: "Ravi", age: 24, city: "Chennai" } },
  { upsert: true }
)

Verify Upserted Document:

db.students.find()

---

📌 Task 3 – MongoDB Query Operators

This task covers Comparison, Logical, Element, Array, and Evaluation operators in MongoDB. All queries are executed on the students collection inside the learning_mongo database.

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1️⃣ Comparison Operators

Find all students whose age is exactly 26

db.students.find({ age: { $eq: 26 } })

Find students whose age is not equal to 26

db.students.find({ age: { $ne: 26 } })

Find students whose age is greater than 24

db.students.find({ age: { $gt: 24 } })

Find students whose age is less than 23

db.students.find({ age: { $lt: 23 } })

Find students who live in either Pune or Satara

db.students.find({ city: { $in: ["Pune", "Satara"] } })

---

2️⃣ Logical Operators

Find students whose age is greater than 24 AND city is Satara

db.students.find({
  $and: [{ age: { $gt: 24 } }, { city: "Satara" }]
})

Find students whose city is Pune OR Navi Mumbai

db.students.find({
  $or: [{ city: "Pune" }, { city: "Navi Mumbai" }]
})

Find students whose age is NOT greater than 25

db.students.find({ age: { $not: { $gt: 25 } } })

Find students who are not from Pune and not younger than 22

db.students.find({
  $and: [
    { city: { $not: { $eq: "Pune" } } },
    { age: { $not: { $lt: 22 } } }
  ]
})

---

3️⃣ Element Operators

Find students who have a profile field

db.students.find({ profile: { $exists: true } })

Find students whose age field type is int

db.students.find({ age: { $type: "int" } })

---

4️⃣ Array Operators

Find students whose subjects contain both Python and Math

db.students.find({ subjects: { $all: ["Python", "Math"] } })

Find students who have exactly 2 subjects

db.students.find({ subjects: { $size: 2 } })

---

5️⃣ Evaluation Operators

Find students whose name starts with "R"

db.students.find({ name: { $regex: "^R" } })

Find students whose subjects contain the word Python (using $text)

db.students.createIndex({ subjects: "text" })
db.students.find({ $text: { $search: "Python" } })

Find students whose age is greater than 25 using $expr

db.students.find({ $expr: { $gt: ["$age", 25] } })

---