MongoDB

MongoDB

MongoDB is an open-source document database and leading NoSQL database. It is written in C++.it is a cross-platform, document oriented database that provides, high performance, high availability, and easy scalability.It works on concept of collection and document.

Syntax:

➤Basic syntax of use DATABASE statement is as follows −

.use DATABASE_NAME 

>use music

➤Your created database (mydb) is not present in list. To display database, you need to insert at least one document into it.

>db.movie.insert({"name":" songdetails"})







➤MongoDB db.dropDatabase() command is used to drop a existing database.

db.dropDatabase()

➤To check the list of available databases by using the command, show dbs.

>show dbs
local      0.78125GB
mydb       0.23012GB
test       0.23012GB

➤MongoDB db.createCollection(name, options) is used to create collection.

db.createCollection(name, options)


➤MongoDB's db.collection.drop() is used to drop a collection from the database.

➤MongoDB's db.collection.drop() is used to drop a collection from the database.

➤MongoDB's db.collection.update() is used to drop a collection from the database.

Syntax: >db.COLLECTION_NAME.update(SELECTION_CRITERIA, UPDATED_DATA)

Example:

> db.songdetails.update({"Song Name":"Roja poonthooddam"},{$set:{"Song Name":"Enkee enathu kavithai"}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

➤ MongoDB's remove() method is used to remove a document from the collection. 

 here,I am going to remove thadsha

> db.students.remove({"Name":"thadsha"})
WriteResult({ "nRemoved" : 1 })

➤ Increase

If we want to increase a total by adding numbers to given we use $inc
Example:

 > db.studentmarks.update({"name":"Mala"},{$inc:{"maths_marks":6}})

➤gt is used as greater symbol

> db.studentmarks.find({"maths_marks":{$gt:50}}).pretty()

It will list the names of student of maths marks greater the 50

➤Update is used to reset data

>db.studentmarks.update({"name":"lucky"},{$set:{"science_marks":75}})

It update the lucky's science marks to 75

➤and

> db.studentmarks.find({$and:[{"maths_marks":{$gt:40}},{"science_marks":{$lt:40}}]}).pretty()

It give the data as both condition is true

or

>db.studentmarks.find({$or:[{"maths_marks":{$gt:40}},{"science_marks":{$lt:40}}]}).pretty()
It give data as one condition is true

Rename

> db.studentmarks.update({"name":"John"},{$rename:{"english_marks":"science_marks"}})

It rename the english_marks as science_marks