using of mongoose in node application
                          <=========================================>

connecting to mongodb using mongoose
========================================>
    const mongoose =require("mongoose");
    mongoose.connect("mongodb://127.0.0.1:27017/StudyStudent");
         Note: The Last name studystudent shows name of database
    mongoose.set('strictQuery', true);


Creating Schema using mongoose.Schema({}) 
============================================>
const StudentRegistrationSchema=mongoose.Schema({
    EnrollmentNumber: String,
    Name: String,
    Gender:String,
    College:String,
    Course:String,
    Year:Number,
    Email:String,
    Contact:String,
    Address:String,
    ProfilePicture:String
});

Creating Collection using mongoose.model("CollectionName",SchemaNAME);
========================================================================>
   const StudentRegistartionData= mongoose.model("StudentRegistartionData",StudentRegistrationSchema);

To insert Entity
==================>
   const varname=new collectionvarName({
        Name:req.body.Name,
        Email:req.body.Email,
        Contact:req.body.Contact,
        Query:req.body.Query
    });
	varname.save();
	
	//Example
	 const query=new Query({
        Name:"Raj",
        Email:"raj@gmail.com",
        Contact:"987654321",
        Query:"Hello G"
    });
    query.save();
	
To fetch/read Data
====================>
    
    coll_Name.find().then((collData)=>{
           console.log(collData);
    }).catch((err)=>{
        console.log(err);
    });

    Example
    ========> 
    Query.find().then((QueryList)=>{

            QueryList.forEach(function(enquiry){
                 Console.log(enquiry.Query);
            });
        });

To filter the entity
======================>
    Model.find()
       Parameters:
           filter «Object|ObjectId»
           [projection] «Object|String|Array[String]» optional fields to return, see Query.prototype.select()
           [options] «Object» optional see Query.prototype.setOptions()
           [callback] «Function»
   
    Model.findById({
        query» Object
    }).then(function(data){
         console.log(data);
    }).catch(function(error){
          console.log(error);
    });
         Parameters:
           id «Any» value of _id to query by
           

To close the connection
===========================>
mongoose.connection.close();


To add some validation
=========================>
//validation can be added at making schema time
const querySchema=mongoose.Schema({
    Name:{
	type:String,
	required:[true,"Pls check the entry no name is specified"]
	},
    Email:String,
    Contact:String,
    Query:String
});


Updating
==================>
     Model.updateMany()
        Parameters:
           filter «Object» 
           update «Object|Array»
           [callback] «Function» params are (error, writeOpResult)

     Example
     ==========>
     Query.updateMany({Name:"Raj"},{Query:"..."},function(err){
          if(err)  console.log(err);
          else console.log("Successfully updated");
     });

     TO UPDATE Only one Data
     =================>
       Model.updateOne()   
             Parameters:
                filter «Object»
                update «Object|Array»
                [callback] «Function» params are (error, writeOpResult)


        Example
        =========>
         Query.updateOne({Name:"Raj"},{Query:"..."},function(err){
            if(err) console.log(err)
            else console.log("Successfully updated");
         });

Deletion
==============>
     To delete one entity
     ======================>
        Model.deleteOne()
            Parameters:
                conditions «Object»
                [options] «Object» optional see Query.prototype.setOptions()
                [callback] «Function»

        Example-
             Query.deleteOne({Name:"Raj"},function(err){
                if(err) console.log(err)
                else console.log("Successfully deleted");
             });


    To delete more than one entity
    ================================>
       Model.deleteMany()
         Parameters:
             conditions «Object»
             [options] «Object» optional see Query.prototype.setOptions()
             [callback] «Function»

      Example-
         Query.updateMany({Name:"Raj"},{Query:"..."},function(err){
               if(err) console.log(err)
               else console.log("Successfully deleted");
         });


To count entity 
====================>
       Model.countDocuments()
           Parameters:
               filter «Object»
               [callback] «Function»


To count entity with some specific condition
================================================>
      Example=> To count the order datewise
               Orders.countDocuments({Date:{}});


Relationship
==============>
      To communicate between different collection we make relation among them
      Let's a collection has some features some string ,some data types.
      When there is a lot of features then it is a good idea to distinguish them making a new relation

          {
              Name:"Raj",
              Address:"PNB",
              fruitLike:"Banana",
              fruitPrice:50,
              fruitfeatures:"Make strong"
          }
          {
              Name:"Raj",
              Address:"PNB",
              fruitLike:"Banana",
              fruit:new_coll_Schema i.e. an embedded doc
          }