mongodb.txt

1. List databases
    show dbs

2. Use db (switch to the database)
    use DATABASE_NAME
    
    Note! if the db exists, it will switch to it, if not it will still switch and it assumes you are creating a new db

3. Show collections
    show collections

4. Create a collections
    db.createCollection("users")

5. Insert a document to the collections
    db.users.insertOne({
        "name": "Manohar Negi",
        "email": "mnegi@abc.com",
        "password": "supersecret",
        "address": "JP Nagar, Bangalore",
        "mobile": 789263311
    })

6. Finding the documents
    Find all
        db.users.find()
    Filter by name
        db.users.find({name: "Manohar Negi"})

7. Projections - getting the colums
    db.users.find(
        { },
        { email: 1, password: 1 , mobile: 0}
    )

8. Conditions
    // mobile not equal (ne)
    db.users.find(
        { mobile: { $ne: 789263311 } }
    )

    // AND criteria
    db.users.find(
        {password: "supersecret", mobile: 789263311}
    )

    // OR criteria
    db.users.find(
        { $or: [ {password: "supersecret"} , { mobile: 789263311 } ] }
    )

    // greater than (gt)
    db.users.find(
        { age: { $gt: 25 } }
    )

    // less than (lt)
    db.users.find(
        { age: { $lt: 25 } }
    )

    // lte = less than or equal
    db.users.find(
        { age: { $gt: 25, $lte: 50 } }
    )

    //WHERE name like "%ka%"
    db.users.find( { name: /ka/ } )

    // WHERE name like "Vi%"
    db.users.find( { name: /^Vi/ } )
    or
    db.users.find( { name: { $regex: /^Vi/ } } )

9. Sorting
    //ORDER BY name ASC
    db.users.find( ).sort({ name: 1 })

    //ORDER BY name DESC
    db.users.find( ).sort({ name: -1 })

10. Count
    //SELECT COUNT(*)
    db.users.count()

    //SELECT COUNT(user_id)
    db.users.count( { status: { $exists: true } } )
    db.users.count( { status: "inactive" } )
    db.users.find( { age: { $gt: 30 } } ).count()

11. distinct
    // SELECT DISTINCT(status)
    db.users.distinct( "status" )

12. Limit

    //LIMIT 1
    db.users.findOne()
    or
    db.users.find().limit(1)

    //LIMIT 5 SKIP 10
    db.users.find().limit(5).skip(10)

13. Explain the query
    db.users.find( { status: "active" } ).explain()

14. Update the document
    //ADD status 
    db.users.updateMany(
        { },
        { $set: { create_at: new Date() } }
    )

    // modify the existing
    db.users.updateMany({ name: { $regex: /^Vi/ } } ,{ $set: {status: 'inactive'}})

    //DROP COLUMN j
    db.users.updateMany(
        { },
        { $unset: { "join_date": "" } }
    )

15. Create index
    db.users.createIndex( { email: 1 } )

16. Delete the collection
    db.users.drop()

17. Drop the database
    db.dropDatabase()