//To use mongodb in an application We have two choices :
         1) Mongo DB driver=>uses same commands as in mongo shell
         2) mongoose

//Learning Mongodb in mongo Shell
        To run mongodb cmd in shell(cmd), type: mongosh

Some Basic command of Mongodb 
++++++++++++++++++++++++++++++++++++++++
      1) show dbs => To show database directory.
      2) use <db_name>=> To create a new database./To go from one database to another one.
      3) db => to know in which db you are.
      4) show collections=> show collections(tables) in current database
      5) To delte an entire database ,firstly switch to that database then use
              db.dropDatabase()
      6) db.coll_name.dropDatabase()To delete a collection

      7) To create a collection named posts
              db.createCollection("posts")


Create Collection
===================>
       1) db.createCollection("posts")
       2) You can also create a collection during the insert process.
          db.collection_name.insertOne(object)

Insertion
============>
To insert the data into a collection
              a) db.collection_name.insertOne({
                        //data in key value pair
                 }) 
              b) db.collection_name.insertMany([  
                        {//data},
                        {//data },
                        {//data}...
                 ])
       

Selection /Finding /Fetching
=============================>
               a)  db.collectionName.find()=>To select data from a collection
           Note:This method accepts a query object. If left empty, all documents will be returned.

               b) db.collectionName.findOne()=>
                   To select only one document, we can also use the findOne() method.
           Note:This method accepts a query object. If left empty, it will return the first document it finds.

          Querying(Filter Data)
          ======================>
               db.collectionNmae.find({//Query in key value pair})
                  Example- db.Tbl_LoginData.find({Email:"raj@gmail.com" })

          Projection
          ===============>
            1) Both find methods accept a second parameter called projection.
            2) This parameter is an object that describes which fields to include in the results.
               db.posts.find({}, {title: 1, date: 1})
                  =>This will show result with title and date
               db.posts.find({}, {_id: 0, title: 1, date: 1})
                  =>This will show result with title and date and not show _id.
            3)We use a 1 to include a field and 0 to exclude a field.





Updation
===========>
       1) db.collectionNmae.updateOne({
                a query object to define which documents should be updated.
             },
             {
               // second parameter is an object defining the updated data
          })
       
       2) db.collectionName.updateMany({Query_object},{Property_object})

       3) Now let's update Password of a document. To do this, we need to use the $set operator.

            db.collectionName.updateOne( {
                    Email:"raj@gmail.com" 
                }
               ,{
                      $set:{  Password:"RAm@gmail1234"  }
            })



Deletion
===========>
        db.coll_name.deleteOne({//Query data})=>
               The deleteOne() method will delete the first document that matches the query provided.
        db.coll_name.deleteMany({//Query Data})


MongoDB Query Operators
=============================>
       There are many query operators that can be used to compare and reference document fields.
       
       Comparision Operators
       ========================>
$eq: Values are equal
$ne: Values are not equal
$gt: Value is greater than another value
$gte: Value is greater than or equal to another value
$lt: Value is less than another value
$lte: Value is less than or equal to another value
$in: Value is matched within an array

        Logical
        ============>
$and: Returns documents where both queries match
$or: Returns documents where either query matches
$nor: Returns documents where both queries fail to match
$not: Returns documents where the query does not match

         Evaluation
         ============>
$regex: Allows the use of regular expressions when evaluating field values
$text: Performs a text search
$where: Uses a JavaScript expression to match documents


          MongoDB Update Operators
          ==========================>
$currentDate: Sets the field value to the current date
$inc: Increments the field value
$rename: Renames the field
$set: Sets the value of a field
$unset: Removes the field from the document



Some Others commands which are rear used
============================================>
         show
         =======>
           'show databases'/'show dbs': Print a list of all available databases.
           'show collections'/'show tables': Print a list of all collections for current database.
           'show profile': Prints system.profile information.
           'show users': Print a list of all users for current database.
           'show roles': Print a list of all roles for current database.
           'show log <type>': log for current connection, if type is not set uses 'global'
           'show logs': Print all logs.

    exit    Quit the MongoDB shell with exit/exit()/.exit
    quit    Quit the MongoDB shell with quit/quit()
    Mongo   Create a new connection and return the Mongo object. Usage: new Mongo(URI, options [optional])
    connect Create a new connection and return the Database object. Usage: connect(URI, username [optional], password [optional])
    it      result of the last line evaluated; use to further iterate
    version Shell version
    load    Loads and runs a JavaScript file into the current shell environment
    enableTelemetry    Enables collection of anonymous usage data to improve the mongosh CLI
    disableTelemetry   Disables collection of anonymous usage data to improve the mongosh CLI
    passwordPrompt     Prompts the user for a password
    sleep              Sleep for the specified number of milliseconds
    print              Prints the contents of an object to the output
    printjson          Alias for print()
    cls                Clears the screen like console.clear()
    isInteractive      Returns whether the shell will enter or has entered interactive mode