Let's start the mongo server. Open a terminal and type:
mongod
This will start the server, now open another terminal and type:
mongo
Now you are inside the mongo instance, you can now create and play with different operations. Let's see which database we are currently in and what are the databases and collections available.
db
show databases
show collections
Commands to create new database is use.
Let's create a database called as learnmongo and then we will create a collection called as class. Inside this class we will add student's name and their age, sample student can be:
Name: Prashant
Age: 25
use learnmongo
db.createCollection('class')
db.class.insert({name: "Prashant", age: 52})
Let's see what data, I have added:
db.class.find()
Okay, I don't want to see _id
db.class.find({}, {_id: 0})
Oops! I made a mistake. My age isn't 52, it's 25. Let me change it back.
db.class.update({name : Prashant}, {$set: {age: 25}})
Displaying everyone whose age is less than 25 years:
db.class.find({$and:[{age : {$lt : 25}}]});
To display everyone whose age is less than 25 years and name is Prashant:
db.class.find({$and:[{age : {$lt : 25}}, {name: "Prashant"}]});
Note: $lt stands for less than and $gt stands for greater than.
Creating Data:
db.class.insert({name: "Ada", age: 20})
Reading Data:
db.class.find()
Updating Data:
db.class.update({name : "Ada"}, {$set: {age: 23}})
Delete Data:
For removing the document:
db.class.remove({name: "Ada"});
For removing the entire collection:
db.class.remove({});
Just in case you are interested in doing an export and import, you can use mongodump and mongorestore command.
Note: In recent version of the mongo, mongodump and mongorestore are not part of official package, you have to download it seperately. You can follow this link.