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Introduction to Mongo Database

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It's been long time, since the last post. Let's get to know about mongo database. So mongo is one of the front runners in nosql databases. Nosql databases do not adhere to rules and principles to standard relational databases. So coming to Mongo it a document oriented database which is written in C++.
 
Mongo is an open source database. It is simple to install more of a plug and play type.
 
Once you are done with the mongo installation To start the mongo server in our local machine. Execute the command in command terminal
 
C:\MongoDB\bin\mongod.exe --config="C:\MongoDB\mongo.config"
 
To start the client in our local machine execute the following command in the command terminal
 
C:\MongoDB\bin\mongo
 
Upon executing we can see the following screen
 

 
 By default there will be a test database created in our mongo database. So it will be connected to that particular database.
 
We can create our own database by executing the following command
 
 use local_test
 
So a database under name local_test will be created. To see the list of databases created we can use the following command
 
show dbs   But upon executing the following command you will not see the database which is created just now local_test.
 
 
 
 
This is because it is an empty database. We need to insert a document to make it visible.
 
In mongo data can be inserted only in Json format.

To insert the data execute the following command
 
db.firstdocument.insert({"Name":"AAA","ID":"101"})
 
Now if we execute show dbs we can see the local_test database being created.
 
When we inserted firstdocument in local_test, automatically a collection is created under that name.So basically documents are stored in collection. We can insert any number of rows(i.e. documents) in a given collections
 
To display total number of collections in a given database
 
show collections
 
 
system.indexes  is implicitly created upon creating a collection. This stores indexes information of all documents
 
To see data inside the collections
 
db.firstdocument.show()
 


_id is a unique value which is automatically generated while inserting a row. we can override _id
value and pass our own value in the following way
 
 



These are some of the basics queries in mongo in the next article we will see how to update,delete operations on databases and collections
 
Hope this article helps you in understanding basic mongo queries

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