Node.js MongoDB

                      Node.js MongoDB

   Hi guys.. you will try it !........

--Today we learn how to connecting  nodejs_mongodb--

 

1.create a Database

*  To create a database in MongoDB, start by creating a MongoClient object, then specify a connection URL with the correct ip address and the name of the database you want to create.

* MongoDB will create the database if it does not exist, and make a connection to it.

Create a Database called ​Uki_student

var MongoClient = require('mongodb').MongoClient;
var url = "mongodb://localhost:27017/Uki_student";

MongoClient.connect(url, function(err, db) {
  if (err) throw err;
  console.log("Database created!");
  db.close();
});

2.Creating a Table

* To create a table in MongoDB, use the createCollection() method:

Create a collection called ​ studentmarks

var MongoClient = require('mongodb').MongoClient;
var url = "mongodb://localhost:27017/Uki_student";

MongoClient.connect(url, function(err, db) {
  if (err) throw err;
  db.createCollection("student_marks", function(err, res) {
    if (err) throw err;
    console.log("Table created!");
    db.close();
  });
});

3.Insert Into Table

* To insert a record into a table in MongoDB, we use the insertOne() method.

* The first parameter of the insertOne() method is an object containing the name(s) and value(s) of each field in the record you want to insert.

* It also takes a callback function where you can work with any errors, or the result of the insertion:

      Create the documents listed in above table

var MongoClient = require('mongodb').MongoClient;
var url = "mongodb://localhost:27017/Uki_student";

MongoClient.connect(url, function(err, db) {
  if (err) throw err;
  var myobj = [

{Name: "Ramana",ID_Number:ukiid_01,Assignment1_Marks:80,Assignment2_Marks:70 },
 {Name: "Thanees",ID_Number:ukiid_02,Assignment1_Marks:60,Assignment2_Marks:50 },

{Name: "Jana",ID_Number:ukiid_03,Assignment1_Marks:79,Assignment2_Marks:48 },

{Name: "Darshan",ID_Number:ukiid_04,Assignment1_Marks:67,Assignment2_Marks:84},

{Name: "Shanka",ID_Number:ukiid_05,Assignment1_Marks:90,Assignment2_Marks:59 }, 

{Name: "Thuva",ID_Number:ukiid_06,Assignment1_Marks:58,Assignment2_Marks:78 },  

{Name: "Jakshan",ID_Number:ukiid_07,Assignment1_Marks:78,Assignment2_Marks:93},

{Name: "Mayoori",ID_Number:ukiid_08,Assignment1_Marks:45,Assignment2_Marks:83},

{Name: "Thadsha",ID_Number:ukiid_09,Assignment1_Marks:90,Assignment2_Marks:87},

{Name: "Dans",ID_Number:ukiid_10,Assignment1_Marks:56,Assignment2_Marks:63},

{Name: "Shama",ID_Number:ukiid_11,Assignment1_Marks:95,Assignment2_Marks:90},{Name: "Abiramy",ID_Number:ukiid_12,Assignment1_Marks:83,Assignment2_Marks:69 },

{Name: "Mino",ID_Number:ukiid_13,Assignment1_Marks:37,Assignment2_Marks:72 },

{Name: "Janu",ID_Number:ukiid_14,Assignment1_Marks:58,Assignment2_Marks:93 },

{Name: "Dilani",ID_Number:ukiid_15,Assignment1_Marks:49,Assignment2_Marks:84},

];
  db.collection("student_marks").insert(myobj, function(err, res) {
    if (err) throw err;
    console.log("Number of records inserted: " + res.insertedCount);
    db.close();
  });
});

4.Node.js MongoDB Query

* When selecting records from a table, you can filter the result by using a query object.

* The first argument of the find() method is a query object, and is used to limit the search.

 

Increase the maths marks of Mayoori by 10Assignment1_Marks

var MongoClient = require('mongodb').MongoClient;
var url = "mongodb://127.0.0.1:27017/Uki_student";
MongoClient.connect(url, function(err, db) {
  if (err) throw err;
  var myquery = { name: "Mayoori" };
  var newvalues = {$ins:{Assignment_Marks:6} };
  db.collection("student_marks").update(myquery, newvalues, function(err, res) {
    if (err) throw err;
    console.log(res.result.nModified + " record updated");
    db.close();
  });
});

5.Node.js MongoDB Select From

-Select One-

* To select data from a table in MongoDB, we can use the findOne() method.

* The findOne() method returns the first occurrence in the selection.

* The first parameter of the findOne() method is a query object. In this example we use an empty query object, which selects all records in a table (but returns only the first record).

-Select All-

* To select data from a table in MongoDB, we can also use the find() method.

* The find() method returns all occurrences in the selection.

* The first parameter of the find() method is a query object. In this example we use an empty query object, which selects all records in a table.

 

 List the names of students who got more than 50 marks in Assignment1_Marks.

var MongoClient = require('mongodb').MongoClient;
var url = "mongodb://localhost:27017/Uki_student";

MongoClient.connect(url, function(err, db) {
  if (err) throw err;
  var options={Assignment1_Marks:1,_id:0}
  db.collection("student_marks").find({Assignment1_Marks:{$gt:50}},options).toArray(function(err, result) {
    if (err) throw err;
    console.log(result);
    db.close();
  });
}); 

6.Node.js MongoDB Update

* You can update records, or documents as it is called in MongoDB, by using the update() method.

* By default, the update() method only updates one document.

* The first parameter of the update() method is a query object defining which document to update.

* The second parameter is an object defining the new values of the document. By default, all fields in the document gets updated, (except the _id field) so remember to set the value of every field, otherwise the value will be left empty.

 

Update Assignment1_Marks=75 to Thadsha

 
var MongoClient = require('mongodb').MongoClient;
var url = "mongodb://127.0.0.1:27017/Uki_Student";

MongoClient.connect(url, function(err, db) {
  if (err) throw err;
  var myquery = { name: "Thadsha" };
  var newvalues = {$set:{Assignment1_Marks:75} };
  db.collection("student_marks").update(myquery, newvalues, function(err, res) {
    if (err) throw err;
    console.log(res.result.nModified + " record updated");
    db.close();
  });
});

7.Node.js MongoDB Remove

* You can delete records, or documents as it is called in MongoDB, by using the remove() method.

* The first parameter of the remove() method is a query object defining which documents to delete.

 

 Remove Assignment2_Marks column/field for Ramana

var MongoClient = require('mongodb').MongoClient;
var url = "mongodb://localhost:27017/Uki_student";

MongoClient.connect(url, function(err, db) {
  if (err) throw err;
  var myquery = {name: "Ramana" }
  var newvalues = {$unset: {Assignment2_Marks: ""} };
  db.collection("student_marks").update(myquery, newvalues, function(err, res) {
    if (err) throw err;
    console.log(res.result.nModified + " record updated");
    db.close();
  });
}); 

8.Node.js MongoDB Drop

* You can delete a table, or collection as it is called in MongoDB, by using the drop() method.

* The drop() method takes a callback function containing the error object and the result parameter which returns true if the collection was dropped successfully, otherwise it returns false.

  

Delete the "student_marks" table:

 

var MongoClient = require('mongodb').MongoClient;
var url = "mongodb://localhost:27017/Uki_students";

MongoClient.connect(url, function(err, db) {
  if (err) throw err;
  db.collection("student_marks").drop(function(err, delOK) {
    if (err) throw err;
    if (delOK) console.log("Table deleted");
    db.close();
  });
});