How to create database in mongodb -(Insert, Display, Remove document)

How to create database in mongodb : In this article, we will look at what is a database and how to create one in MongoDB. We will also look at which command is used to create a database, create a collection, insert, display ,remove the documents in the database and drop the collection. Once you have a database name, you will need to give it a name. Once you have a name, you can create another collection with the same name.

what is a database?

MongoDB is a document-oriented database program. It uses JSON-like documents with optional schemas to store data. It is developed by MongoDB Inc. and is licensed under the Server Side Public License. Some distributions consider this license non-free, though. In this article, we will look at the different ways that MongoDB can be used.

To create a MongoDB database, you first need to create a database name. You can use any ASCII character for a database name, but it should not contain any spaces or reserved words like “system”. Once the database name is chosen, you can create the document. You can also refer to it as “object” in the MongoDB documentation.

MongoDB also supports multiple databases. Each database gets its own set of files on the file system. Each database can store multiple documents, each with different fields. Using a database, you can store data from multiple sources, such as a web service. This allows you to store large amounts of data, and to easily search through it.

Each MongoDB document has a unique identifier (id). This identifies each document. This is referred to as the primary key of a document in an RDBMS. When a document is created, the database automatically creates an _id field for it. A MongoDB database is considered schema-free, so it can store documents with different structures. You do not need to specify the column datatype for each document, which makes MongoDB an attractive option for developers and data scientists.

How can I create a database?

Show Databases:

show dbs command is uesd to list all databases on a MongoDB server. This will show you the database name, as well as the size of the database in gigabytes.

MongoDB is a database management system that focuses on scalability and availability. It stores data as collections of JSON documents. Since the data is not structured in a fixed way, MongoDB is ideal for high-volume storage in a modern distributed system. To create a database, run the command md create or insert a document into the database.

To use the MongoDB command-line interface, first access the MongoDB cluster using the “mongodb shell.” This program lets you enter commands into the software system. It also requires a user account and password. After you have the software installed, you can start creating databases.

You can create as many databases as you want. Once you have a database, you can insert collections into it. A database is similar to a table in SQL, except MongoDB lets you create an unlimited number of collections. When inserting data, MongoDB will save it as a JSON object or a key-value pair. When storing data in MongoDB, you must specify the database name and collection name.

Which command is used to create a database in MongoDB

The use Command

MongoDB uses DATABASE_NAME to create a database. If the database doesn’t exist, it will create it. Otherwise it will return the current database.

Syntax:

The basic syntax for use DATABASE is as follows –

Use DATABASE_NAME

Example:

Use DATABASE to access a database named.

>use mydb 
changed to db mydb

Use the command DB to check the database you have selected.

>db mydb

You can use the show database command to view your database list.

>show dbs
local 0.78125GB 
test 0.23012GB

To create a database in MongoDB, use the use command. This command creates a new database with the name “mydb”. Once the database is created, you can start inserting records into it. Alternatively, you can use the show dbs command to see all databases.

Insert document into a database in MongoDB

You will need a MongoClient object to connect to MongoDB. Once you’ve created your connection, you can use the insert() command to add a record to a database collection. After you’ve added a record, you can use the show dbs command to see what you’ve created.

1. Inserting document after creating the collection:

Insert a Document without Specifying  _id Field

2. Inserting single document while creating the collection:

If the collection does not exist, then the insert() method creates the collection.

3. Insert a Document with Specifying  _id Field:

4. Inserting multiple document:

5. Inserting multiple documents using a array variable:

MongoDB’s GUI makes it easy to create and modify databases. You can add documents and modify them using the interface. To add a document to a MongoDB collection, simply click on “Insert document.” You’ll see a dialogue box with the details of the document. MongoDB also supports Mapreduce and replication.

Although MongoDB does not have an explicit CREATE DATABASE statement, it makes it easy to create a database with the same name. However, you must first insert data into the database in order for it to exist. In older versions of MongoDB, you must use the insert() method to insert data into the database. Otherwise, you’ll get an invalid function error.

MongoDB offers high availability through replica sets. Each replica set consists of two or more mongod instances. Each instance can assume a primary or secondary role. The primary replica performs all read and write operations, while the secondary replicas serve as back-ups.

Does MongoDB create database automatically?

You can also create a database on your own using the MongoDB command line interface. To do this, you first need to connect to the MongoDB cluster using the MongoDB Shell. To do this, you’ll need a user account and password. Once you have these, you’ll be able to run the command.

When you insert new documents into a database, MongoDB will create a collection for each one. You can also see the collections that MongoDB has created for you by running the show dbs command. This will give you an idea of how many collections are available. You can also delete the database that has been created by using the drop or drip command.

You can also create a database by defining the name of the collection. For example, if you’re using MongoDB for your application, you should name the collection with a unique Object ID. A MongoDB collection has multiple documents that are stored in one container, and you can create as many as you need.

Using the MongoDB Compass command will also help you create a database. It will connect to the MongoDB server and open a pop-up window asking you to define the name of the database and collection. From there, you can then insert the document into the database.

Create A MongoDB Database

You can create a MongoDB database with a few simple steps. First, register for an account on the MongoDB website. Next, select a cluster, which is a container for databases. Once you’ve created a cluster, you can control its behavior through the command line interface.

To create a database with a MongoDB cluster, follow the following steps. You’ll need a user account and password for your system. In addition, you’ll need to install the MongoDB shell. This program provides powerful command line support and supports many of the most commonly used CRUD operations.

Next, you need to enter a name for the database. Typically, the database name is called DATABASE_NAME. Using this name in a query will make it easier to identify a database. Once you have a database name, you can use a mongodb command to see the contents of the database.

To create a MongoDB database, use the command mongodb. Then, you can add records into it. You can even insert more than three documents at a time! Once you’ve finished, you’re ready to start using MongoDB. Once you’ve set up the database, you can start inserting records into it to create a collection.

Before you can create a MongoDB database, you’ll need to create an initial collection. This is a mandatory step. You’ll also need to provide a name for your collection. In addition, you can create new collections by hand.

Display the documents from database in MongoDB

1. Find all the documents present in the collection

2. Find all the documents present in the collection in user readable format

3. Find all the documents present in the collection in JSON format

4. Find all the documents present in the collection by passing empty document:

db.student.find({})

5. Find all the document that matches the given filter query(i.e., age:18):

db.student.find({age:18})

6. Find the embedded document that matches the given filter query:

db.student.find({score:{math: 230, science: 234}})

7. Display only the specified fields(Using Projection):

db.student.find({},{name:1, _id:0})

8. Display only two documents using the limit() method:

db.student.find().limit(2)

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Remove Documents from Database

1. Remove All Documents that Match a Condition

To remove the documents that match a deletion criteria, call the “remove()” method with the <query> parameter:

The following operation removes all the documents from the collection ‘subject’ where ‘name’ is eq ‘panda’:

2. Remove All Documents from a Collection

To remove all documents in a collection, call the “remove” method with an empty query document “{}”. The following operation deletes all documents from the class collection:

db.subject.remove( { } )

Drop a Collection in a Database

1. Drop a Collection Using Default Write Concern

The following operation drops the students collection in the current database.

db.collection.drop()

db.subject.drop()

MongoDB has advantages over RDBMS

  • Schema Less – MongoDB, a document database that holds multiple documents in one collection, is called Schema. The number of fields, the content, and the size of the document may differ between documents.
  • The structure of one object is obvious.
  • No complicated joins
  • Deep query-ability. MongoDB supports dynamic querying on documents with a document-based language query language nearly as powerful than SQL.
  • Tuning.
  • Scalability of – MongoDB makes it easy to scale.
  • Not needed: Conversion/mapping application objects to databases objects
  • Internal memory is used to store the working set (windowed), allowing faster access to data.

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MongoDB: Why use it?

  • Document-Oriented Storage Data is stored as JSON documents.
  • Any attribute can be index
  • High availability and replication
  • Auto-Sharding
  • Rich queries
  • Rapid updates in-place
  • MongoDB provides professional support

MongoDB: Where can I use it?

  • Big Data
  • Content Management and Delivery
  • Mobile and Social Infrastructure
  • User Data Management
  • Data Hub

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