Mongo Db - D B M S

• Theory
• Basic Commands
• Sort Documents
• Filter Data
• Delete

Theory

• Basic
  • Compass => To deal with Database in GUI form
  • ATLAS (Managed MongoDB Hosting | Database-as-a-Service) => Database on the Cloud
  • mongod (Mongo Daemon) => Host process for the database
  • mongo => Command-line shell that connects to a specific instance of mongod
  • Structure
    • SQL => Database, Tables, Rows, Column
    • MySQL (Mongo DB) => Database > Collections (JS Objects) > Documents (BSON) > Fields
• Install
  • Search Install MongoDB > Click on Install MongoDB community edition > Click on Get MongoDB
  • Software > Community Server > Download
  • Install
  • Add its bin path to Environmental Variables (C:\Program Files\MongoDB\Server\4.4\bin) > Now you can access it through PowerShell
• Mongo Compass
  • Connect to Local MongoD
    • Fill in connection fields individually > Connect
  • To create a Database
    • After starting Server > Create Database > Write Database Name & Collection Name > Create Database
    • Click on DatabaseName > Click on CollectionName > Add Data > Insert Document > Write your data > Insert

Basic Commands

• mongosh --version => Check monosh Version
• mongosh "YOUR_CONNECTION_STRING" --username YOUR_USER_NAME => Start the Mongo Shell
• db; => Show Current Database
• show dbs => Show All Databases
• use blog => Create Or Switch Database
• db.dropDatabase(); => Drop Database
• db.createCollection("posts"); => Create Collection
• show collections => Show Collections
• Insert Document

    db.posts.insertOne({
        title: "Post 1",
        body: "Body of post.",
        category: "News",
        likes: 1,
        tags: ["news", "events"],
        date: Date(),
    });
  

• Insert Multiple Documents

    db.posts.insertMany([
        {
            title: "Post 2",
            body: "Body of post.",
            category: "Event",
            likes: 2,
            tags: ["news", "events"],
            date: Date(),
        },
        {
            title: "Post 3",
            body: "Body of post.",
            category: "Tech",
            likes: 3,
            tags: ["news", "events"],
            date: Date(),
        },
    ]);
  

• db.posts.find(); => Find All Documents
• Find Documents with Query

    db.posts.find({
        category: "News",
    });
  

Sort Documents

• Ascending

    db.posts.find().sort({
        title: 1,
    });
  

• Descending

    db.posts.find().sort({
        title: -1,
    });
  

Filter Data

• Count Documents

    db.posts.find().count();
    db.posts
        .find({
            category: "news",
        })
        .count();
  

• db.posts.find().limit(2); => Limit Documents
• Chaining

    db.posts.find().limit(2).sort({
        title: 1,
    });
  

• Find One Document

    db.posts.findOne({
        likes: {
            $gt: 3,
        },
    });
  

• Update Document

    db.posts.updateOne(
        {
            title: "Post 1",
        },
        {
            $set: {
                category: "Tech",
            },
        }
    );
  

• Update Document or Insert if not Found

    db.posts.updateOne(
        {
            title: "Post 6",
        },
        {
            $set: {
                title: "Post 6",
                body: "Body of post.",
                category: "News",
            },
        },
        {
            upsert: true,
        }
    );
  

• Increment Field ( $inc )

    db.posts.updateOne(
        {
            title: "Post 1",
        },
        {
            $inc: {
                likes: 2,
            },
        }
    );
  

• Update Multiple Documents

    db.posts.updateMany(
        {},
        {
            $inc: {
                likes: 1,
            },
        }
    );
  

• Rename Field

    db.posts.updateOne(
        {
            title: "Post 2",
        },
        {
            $rename: {
                likes: "views",
            },
        }
    );
  

Delete

• Delete a Document

    db.posts.deleteOne({
        title: "Post 6",
    });
  

• Delete Multiple Documents

    db.posts.deleteMany({
        category: "Tech",
    });
  

• Greater & Less Than

    db.posts.find({
        views: {
            $gt: 2,
        },
    });
    db.posts.find({
        views: {
            $gte: 7,
        },
    });
    db.posts.find({
        views: {
            $lt: 7,
        },
    });
    db.posts.find({
        views: {
            $lte: 7,
        },
    });