AI &DS MONGO DB EXPERIMENT IN CLOUD ERA

sudo rm -rf /usr/local/mongodb

wget http://fastdl.mongodb.org/linux/mongodb-linux-i686-2.6.12.tgz

tar -xvzf mongodb-linux-i686-2.6.12.tgz

sudo mv mongodb-linux-i686-2.6.12 /usr/local/mongodb

file /usr/local/mongodb/bin/mongo

Start MongoDB Server

First create data directory (only first time):

sudo mkdir -p /data/db
sudo chmod -R 777 /data

/usr/local/mongodb/bin/mongod --dbpath /data/db

You will see logs like:

waiting for connections on port 27017


Open Mongo Shell (New Terminal)
Open a new terminal window and run:
/usr/local/mongodb/bin/mongo

You will see:
>
> show dbs

>use trainingdb

> 

db.students.insert([

 {name:"Ravi", age:22, course:"Hadoop", marks:75},

 {name:"Anita", age:21, course:"MongoDB", marks:85},

 {name:"Suresh", age:23, course:"Hadoop", marks:65},

 {name:"Priya", age:22, course:"Spark", marks:90},

 {name:"Kiran", age:24, course:"MongoDB", marks:70},

 {name:"Meena", age:21, course:"Hadoop", marks:88},

 {name:"Arun", age:23, course:"Spark", marks:60}

])

>

COUNT Function

Count total documents:

db.students.count()

Count with condition:

db.students.count({course:"Hadoop"})

---

 SORT Function

Sort by marks ascending:

db.students.find().sort({marks:1})

Sort by marks descending:

db.students.find().sort({marks:-1})

Sort by age:

db.students.find().sort({age:1})

---

 LIMIT Function

Top 3 students:

db.students.find().limit(3)

Top 3 highest marks:

db.students.find().sort({marks:-1}).limit(3)

---

 SKIP Function

Skip first 2 records:

db.students.find().skip(2)

Pagination example (skip 2, show next 3):

db.students.find().skip(2).limit(3)

---

 AGGREGATE Function (Important)

Aggregation framework example.

---

🔹 Total number of students per course

db.students.aggregate([
 { $group: { _id: "$course", totalStudents: { $sum: 1 } } }
])

---

🔹 Average marks per course

db.students.aggregate([
 { $group: { _id: "$course", avgMarks: { $avg: "$marks" } } }
])

---

🔹 Maximum marks per course

db.students.aggregate([
 { $group: { _id: "$course", maxMarks: { $max: "$marks" } } }
])

---

🔹 Minimum marks per course

db.students.aggregate([
 { $group: { _id: "$course", minMarks: { $min: "$marks" } } }
])

---

🔹 Sort after aggregation

db.students.aggregate([
 { $group: { _id: "$course", avgMarks: { $avg: "$marks" } } },
 { $sort: { avgMarks: -1 } }
])

---

STOP MONGO DB

If  you started MongoDB like this:

/usr/local/mongodb/bin/mongod --dbpath /data/db

Then simply go to that terminal and press:

CTRL + C