{"id":229,"date":"2017-12-12T07:38:23","date_gmt":"2017-12-12T07:38:23","guid":{"rendered":"https:\/\/blinksql.com\/?p=229"},"modified":"2017-12-12T07:38:23","modified_gmt":"2017-12-12T07:38:23","slug":"mongodb","status":"publish","type":"post","link":"https:\/\/blinksql.com\/?p=229","title":{"rendered":"MongoDB"},"content":{"rendered":"

Features:<\/strong><\/p>\n

->MongoDB is a No SQL database. It is an open-source, cross-platform, document-oriented database written in C++.C->\u00a0It stores data as documents, so it is known as document oriented database.<\/p>\n

->\u00a0documents are separated by “.”<\/p>\n

NoSQL Database:<\/strong><\/p>\n

-> It doesn’t use tables for storing data.<\/p>\n

->\u00a0It is generally used to store big data and real-time web applications.<\/p>\n

Advantages:<\/strong><\/p>\n

-> No schema -one collection holds different documents.<\/p>\n

-> There may be\u00a0difference between number of fields, content and size of the document\u00a0from one to other.<\/p>\n

-> No complex joins<\/p>\n

-> Facility of deep query<\/p>\n

-> It is very esay to upgrade and light weight.<\/p>\n

-> It\u00a0uses internal memory for storing working sets\u00a0and this is the reason of its fast access than RDBMS.<\/p>\n

Comparaison with RDBMS:<\/strong><\/p>\n

-> Collection is used like a table in mangodb.<\/p>\n

->\u00a0MongoDB is almost 100 times faster.<\/p>\n

->\u00a0MongoDB is a document oriented database in which data is written in BSON format\u00a0 \u00a0 \u00a0which is a JSON like format not like\u00a0multiple schema and in each schema we create tables to store data in RDBMS.<\/p>\n

Data Types:<\/strong><\/p>\n

Min\/Max Keys:<\/strong> This datatype compare a value against the lowest and highest bson elements<\/p>\n

MongoDB Shell :<\/strong><\/p>\n

-> This is a JavaScript shell that allows interaction with MongoDB instance from the command line.<\/p>\n

-> If we want to create a table, we should name the table and define its column and each column’s data type.<\/p>\n

Note: This is an\u00a0editor in mango DB\u00a0 like an sql editor in RDBMS.<\/p>\n

Create Database:<\/strong><\/p>\n

->\u00a0There is no create database command in MongoDB.<\/p>\n

->\u00a0 In MongoDB you don’t need to create a database manually because MongoDB will create it automatically when you save the value into the defined collection at first time.<\/p>\n

cmd: use\u00a0DATABASE_NAME\u00a0<\/strong><\/p>\n

Note:\u00a0<\/strong>If the database already exists, it will return the existing database. Otherwise creates new database with the given name.<\/p>\n

Check the currently selected database:<\/strong><\/p>\n

cmd: db\u00a0\u00a0<\/strong><\/p>\n

Check the database list:<\/strong><\/p>\n

cmd:show dbs<\/strong><\/p>\n

Note:<\/strong> To see the database in the list it must have atleast single document in it.<\/p>\n

DropDatabase:<\/strong><\/p>\n

The dropDatabase command is used to drop a database. It also deletes the associated data files. It operates on the current database.<\/p>\n

cmd: db.dropDatabase()\u00a0\u00a0<\/strong><\/p>\n

Note:\u00a0<\/strong>In the case we have not selected any database, it will delete default “test” database.<\/p>\n

-> To delete the database sampledb first\u00a0 go to the database using the cmd<\/p>\n

cmd: use\u00a0sampledb<\/strong><\/p>\n

-> Then use the below cmd to drop the database.<\/p>\n

cmd: db.dropDatabase()\u00a0\u00a0<\/strong><\/p>\n

CreateCollection:<\/strong><\/p>\n

MongoDB creates collection automatically when you insert some documents. If we want to create it manually we can use the cmd.<\/p>\n

Syntax: db.createCollection(name<\/span>,\u00a0options)\u00a0 \u00a0<\/strong><\/p>\n

Name: <\/strong>It\u00a0is a string type, specifies the name of the collection to be created.<\/p>\n

Options: <\/strong>It\u00a0<\/strong>\u00a0is a document type, specifies the memory size and indexing of the collection. It is an optional parameter.<\/p>\n

Eg:db.createCollection(“Employee”<\/span>)\u00a0\u00a0<\/strong><\/p>\n

To<\/strong>\u00a0check the created collection:<\/strong><\/p>\n

cmd: show\u00a0collections\u00a0\u00a0<\/strong><\/p>\n

MongoDB create collection automatically:<\/strong><\/p>\n

Insert a document named John into a collection named Employee. The operation will create the collection if the collection does not currently exist.<\/p>\n

cmd:db.Employee.insert<\/span>({“name”<\/span>\u00a0:\u00a0“John”<\/span>})<\/strong><\/p>\n

To see the inserted document:<\/strong><\/p>\n

cmd:db.collection_name.find()<\/strong><\/p>\n

To drop a collection:<\/strong><\/p>\n

It completely removes a collection from the database and does not leave any indexes associated with the dropped collections.<\/p>\n

Synatx: db.COLLECTION_NAME.drop<\/span>()\u00a0\u00a0<\/strong><\/p>\n

Eg:db.Employee.drop<\/span>()\u00a0\u00a0<\/strong><\/p>\n

Note:<\/strong>\u00a0The drop command returns true if it successfully drops a collection. It returns false when there is no existing collection to drop.<\/p>\n

Insert documents:<\/strong><\/p>\n

It is used to add or insert new documents into a collection in your database.<\/p>\n

Syntax:db.COLLECTION_NAME.insert<\/span>(document)\u00a0\u00a0<\/strong><\/p>\n

Eg: db.sampledb.insert<\/span>(<\/p>\n

{<\/p>\n

course:\u00a0“java”<\/span>,<\/p>\n

details:\u00a0{<\/p>\n

duration:\u00a0“6\u00a0months”<\/span>,<\/p>\n

Trainer:\u00a0“Sonoo\u00a0jaiswal”<\/span><\/p>\n

},<\/p>\n

Batch:\u00a0[\u00a0{\u00a0size<\/span>:\u00a0“Small”<\/span>,\u00a0qty:\u00a015\u00a0},\u00a0{\u00a0size<\/span>:\u00a0“Medium”<\/span>,\u00a0qty:\u00a025\u00a0}\u00a0],<\/p>\n

category:\u00a0“Programming\u00a0language”<\/span><\/p>\n

}<\/p>\n

)<\/p>\n

Note:<\/strong> There are another two ways to insert the documents into the collection using arrays and bulk insert.<\/p>\n

\u00a0Upsert:<\/strong><\/div>\n
-> Upsert is an operation that performs either an update of existing document or an insert of new document if the document to modify does not exist.<\/div>\n
->\u00a0“db.collection.update()”\u00a0 and “db.collection.save()” methods\u00a0add new documents through an operation called upsert.<\/div>\n
<\/div>\n
Update:<\/strong>update() method is used to update or modify the existing documents of a collection.<\/div>\n
Syntax:db.COLLECTION_NAME.update<\/span>(SELECTIOIN_CRITERIA,\u00a0UPDATED_DATA)\u00a0\u00a0<\/strong><\/div>\n

-> To update the existing course “java” into “android”<\/p>\n

cmd:db.Employee.update<\/span>({‘course’<\/span>:‘java’<\/span>},{$set<\/span>:{‘course’<\/span>:‘android’<\/span>}})\u00a0\u00a0<\/strong><\/p>\n

To delete documents from a collection:<\/strong><\/p>\n

Syntax:db.collection_name.remove\u00a0(DELETION_CRITERIA)<\/p>\n

Eg:db.Employee.remove({})<\/p>\n

-> The above cmd is used to remove all the documents from the collection. It does not remove indexes.<\/p>\n

Remove all documents that match a condition:<\/strong><\/p>\n

cmd:db.Employee.remove(\u00a0{\u00a0type\u00a0:\u00a0“programming\u00a0language”<\/span>\u00a0}\u00a0)\u00a0\u00a0<\/strong><\/p>\n

-> It will remove all documents from the Employee collection where the type field is equal to programming language.<\/p>\n

Remove a single document that match a condition:<\/strong><\/p>\n

-> It will remove a single document from the Employee collection where the type field is equal to programming language.<\/p>\n

cmd:db.Employee.remove(\u00a0{\u00a0type\u00a0:\u00a0“programming\u00a0language”<\/span>\u00a0},\u00a01\u00a0)\u00a0\u00a0<\/strong><\/p>\n

Retrieve documents from a collection:<\/strong><\/p>\n

Syntax:<\/p>\n

db.COLLECTION_NAME.find({})<\/p>\n

or<\/p>\n

db.COLLECTION_NAME.find()<\/p>\n

limit():<\/strong><\/p>\n

We have a lot of fields in collection of our database and have to retrieve only 1 or 2. In such case, limit() method is used.<\/p>\n

cmd:db.COLLECTION_NAME.find().limit(NUMBER)\u00a0 \u00a0<\/strong><\/p>\n

skip():<\/strong><\/p>\n

This method is used to skip the document. It is used with find() and limit() methods.<\/p>\n

Syntax:db.COLLECTION_NAME.find().limit(NUMBER).skip(NUMBER)\u00a0 \u00a0<\/strong><\/p>\n

Eg:db.Employee.find().limit(1).skip(2)<\/p>\n

->\u00a0Here the skip() method has skipped first and second documents and shows only third document.<\/p>\n

sort() :<\/strong><\/p>\n

This method is used to sort the documents in the collection<\/p>\n

    \n
  • 1 is used for ascending order sorting.<\/li>\n
  • -1 is used for descending order sorting.<\/li>\n<\/ul>\n

    Syntax:db.COLLECTION_NAME.find().sort({KEY<\/span>:1})\u00a0\u00a0<\/strong><\/p>\n

    Eg:db.Employee.find().sort({“Course”<\/span>:-1})<\/p>\n

    <\/div>\n","protected":false},"excerpt":{"rendered":"

    Features: ->MongoDB is a No SQL database. It is an open-source, cross-platform, document-oriented database written in C++.C->\u00a0It stores data as documents, so it is known as document oriented database. ->\u00a0documents…<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_eb_attr":""},"categories":[1],"tags":[],"yoast_head":"\nMongoDB - Blink SQL<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/blinksql.com\/?p=229\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"MongoDB - Blink SQL\" \/>\n<meta property=\"og:description\" content=\"Features: ->MongoDB is a No SQL database. 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