Database models define the structure, relationships, and operations that can be performed on a database. Different database models are used based on the specific needs of an application or organization. Here are the most common types of database models:

1. Hierarchical Database Model

• Structure: Data is organized in a tree-like structure with a single root, where each record has a single parent but can have multiple children.
• Usage: Best for applications with a clear hierarchical relationship, like organizational structures or file systems.
• Example: IBM’s Information Management System (IMS).
• Advantages: Fast access to data through parent-child relationships.
• Disadvantages: Rigid structure; difficult to reorganize or restructure.

2. Network Database Model

• Structure: Data is organized in a graph structure, where each record can have multiple parent and child records, forming a network of relationships.
• Usage: Useful for complex relationships, such as in telecommunications or transportation networks.
• Example: Integrated Data Store (IDS).
• Advantages: Flexible representation of complex relationships.
• Disadvantages: Complex design and navigation; can be difficult to maintain.

3. Relational Database Model

• Structure: Data is organized into tables (relations) where each table consists of rows (records) and columns (fields). Relationships between tables are managed through keys.
• Usage: Widely used in various applications, including finance, retail, and enterprise software.
• Example: MySQL, PostgreSQL, Oracle Database, Microsoft SQL Server.
• Advantages: Simplicity, data integrity, flexibility in querying through SQL.
• Disadvantages: Can be slower for very large datasets or highly complex queries.

4. Object-Oriented Database Model

• Structure: Data is stored as objects, similar to objects in object-oriented programming. Each object contains both data and methods for processing the data.
• Usage: Suitable for applications that require the modeling of complex data and relationships, such as CAD, CAM, and multimedia databases.
• Example: db4o, ObjectDB.
• Advantages: Seamless integration with object-oriented programming languages, reusability of objects.
• Disadvantages: Complexity, not as widely adopted as relational databases.

5. Document-Oriented Database Model

• Structure: Data is stored in document collections, with each document being a self-contained piece of data often in JSON, BSON, or XML format.
• Usage: Ideal for content management systems, real-time analytics, and big data applications.
• Example: MongoDB, CouchDB.
• Advantages: Flexible schema design, scalability, ease of storing hierarchical data.
• Disadvantages: May require denormalization, leading to potential data redundancy.

6. Key-Value Database Model

• Structure: Data is stored as key-value pairs, where each key is unique, and the value can be a string, number, or more complex data structure.
• Usage: Best for applications requiring fast access to simple data, such as caching, session management, and real-time analytics.
• Example: Redis, DynamoDB, Riak.
• Advantages: High performance, simplicity, scalability.
• Disadvantages: Limited querying capabilities, lack of complex relationships.

7. Column-Family Database Model

• Structure: Data is stored in columns rather than rows, with each column family containing a set of columns that are logically related.
• Usage: Suitable for distributed databases, handling large volumes of data across multiple servers.
• Example: Apache Cassandra, HBase.
• Advantages: High write and read performance, efficient storage of sparse data.
• Disadvantages: Complexity in design and maintenance, not as flexible for ad-hoc queries.

8. Graph Database Model

• Structure: Data is stored as nodes (entities) and edges (relationships) forming a graph. Each node represents an object, and edges represent the relationships between objects.
• Usage: Ideal for social networks, recommendation engines, fraud detection, and any scenario where relationships between entities are crucial.
• Example: Neo4j, Amazon Neptune.
• Advantages: Efficient traversal and querying of complex relationships, flexible schema.
• Disadvantages: Not as efficient for operations on large sets of unrelated data.

9. Multimodel Database

• Structure: Supports multiple data models (e.g., relational, document, graph) within a single database engine.
• Usage: Useful for applications that require different types of data storage and querying mechanisms.
• Example: ArangoDB, Microsoft Azure Cosmos DB.
• Advantages: Flexibility, ability to handle diverse data requirements within a single system.
• Disadvantages: Complexity in management and optimization.

10. Time-Series Database Model

• Structure: Specifically designed to handle time-series data, where each record is associated with a timestamp.
• Usage: Best for applications like monitoring, logging, and real-time analytics where data changes over time.
• Example: InfluxDB, TimescaleDB.
• Advantages: Optimized for handling and querying large volumes of time-stamped data.
• Disadvantages: Limited use cases outside of time-series data.

11. NoSQL Database Model

• Structure: An umbrella term for various non-relational database models, including key-value, document, column-family, and graph databases.
• Usage: Ideal for handling unstructured or semi-structured data, and scenarios requiring high scalability and flexibility.
• Example: MongoDB, Cassandra, Couchbase, Neo4j.
• Advantages: Flexibility, scalability, high performance for specific use cases.
• Disadvantages: Lack of standardization, potential data consistency challenges.

Summary

Each database model serves different purposes, and the choice of model depends on the specific requirements of the application, such as data structure, relationships, performance needs, and scalability. While relational databases are still the most widely used, NoSQL and specialized databases have become increasingly important for handling diverse data types and large-scale applications.

Hosting your own WordPress website is interesting right!! Ok, come on let’s do it!!

We are going to do this practical from Scratch. From the Creation of our Own VPC, Subnets, Internet Gateway, Route tables to Deployment of WordPress.

Here, we are going to use Amazon Web Service’s RDS service for hosting our own WordPress site. Before that, let’s take a look at a basic introduction to RDS service.

Amazon Relational Database Service is a distributed relational database service by Amazon Web Services (AWS). It is a web service running in the cloud designed to simplify the setup, operation, and scaling of a relational database for use in applications. Administration processes like patching the database software, backing up databases and enabling point-in-time recovery are managed automatically.

Features of AWS RDS

• Lower administrative burden. Easy to use
• Performance. General Purpose (SSD) Storage
• Scalability. Push-button compute scaling
• Availability and durability. Automated backups
• Security. Encryption at rest and in transit
• Manageability. Monitoring and metrics
• Cost-effectiveness. Pay only for what you use

Ok, let’s jump onto the practical part!!

We will do this practical from scratch. Since it will be big, so we divided this into 5 small parts namely

• Creating a MySQL database with RDS
• Creating an EC2 instance
• Configuring your RDS database
• Configuring WordPress on EC2
• Deployment of WordPress website

Creating a MySQL database with RDS

Before that, we have to do two pre-works namely the Creation of Virtual Private Cloud(VPC), Subnets and Security groups. These are more important because in order to have a reliable connection between WordPress and MySQL database, they should be located in the same VPC and should have the same Security Group.

Since Instances are launched on Subnets only, Moreover RDS will launch your MySQL database in EC2 instance only that we cannot able to see since it is fully managed by AWS.

We are going to create our own VPC. For that, we have to specify IP range and CIDR. We specified IP and CIDR as 192.168.0.0/16.

What is CIDR?. I explained this in my previous blog in very detail. You can refer here.

Lets come to the point. After specifying the IP range and CIDR, enter your VPC name.

Now, VPC is successfully created with our specified details.

Next step is to launch the subnet in the above VPC.

For Creating Subnets, you have to specify which VPC the lab should launch. We already have our own VPC named “myvpc123”.

And then we have to specify the range of Subnet IP and CIDR. Please note that the Subnet range should come under VPC range, it should not exceed VPC range.

For achieving the property of High Availability, We have to launch minimum two subnets, so that Amazon RDS will launch its database in two subnets, if one subnet collapsed means, it won’t cause any trouble.

Now, two Subnets with their specified range of IPs and CIDR are launched successfully inside our own VPC and they are available.

Next step is to create a security group in order to secure the WordPress and MySQL databases. Note that both should have the same Security Group or else it won’t connect.

For creating a Security Group, we have to specify which VPC it should be launched and adding a Description is mandatory.

Then we have to specify inbound rules, for making this practical simple, we are allowing all traffic to access our instance.

Now, the Security Group is successfully created with our specified details.

Now let’s jump into part 1 which is about Creating a MySQL database with RDS.

Select Create database, then select Standard create and specify the database type.

Then you have to specify the Version. Version plays a major role in MySQL when integrating with WordPress, so select the compactible version or else it will cause serious trouble at the end. Then select the template, here we are using Free-tier since it won’t be chargeable.

Then you have to specify the credentials such as Database Instance name, Master username and Master password.

Most important part is a selection of VPC, you should select the same VPC where you will launch your EC2 instance for your WordPress and we can’t modify the VPC once the database is created. Then select the Public access as No for providing more security to our database. Now, the people outside of your VPC can’t connect to your database.

Then you have to specify the security group for your database. Note that the Security Group for your database and WordPress should be the same or else it will cause serious trouble.

Note that Security Groups is created per VPC. After selecting Security Group, then click Ok to create the RDS database.

Creating an EC2 instance

Before creating an instance, there should be two things you configured namely Internet Gateway and Route tables. It is used for providing outside internet connectivity to an instance launched in the subnet.

Internet Gateway is created per VPC. First, we have to create one new Internet Gateway with the specified details.

Then you have to attach Internet Gateway to the VPC

Next step is to create Routing tables. Note that Route table is created per Subnet.

We have to specify which VPC in which your subnet is available to attach routing table with it, specify Name and click create to create the route table.

Then click Edit route to edit the route details namely destination and target. Enter destination as 0.0.0.0/0 for accessing any IP anywhere on the Internet and target is your Internet Gateway.

After entering the details, click Save routes.

We created a Route table, then we have to attach that table to your Subnet. For that click Edit route table association and select your subnet where you want to attach the route table with it.

Now, lets jump into the task of creating an EC2 instance.

First, you have to choose the AMI image in which you used for creating an EC2 instance, here I selected Amazon Linux 2 AMI for that.

Then you have to select Instance type, here I selected t2.micro since it comes under free tier.

Then you have to specify the VPC, Subnet for your instance and you have to enable Auto-assign Public IP in order to get your Public IP to your instance.

Then you have to add storage for your instance. It is optional only.

Then you have to specify the tags which will be more useful especially for automation.

Then you have to select the Security Group for your instance. It should be the same as your database have.

And click Review and Launch. Then you have to add Keypair to launch your EC2 instance. If you didn’t have Keypair means, you can create at that time.

Configuring your RDS database

At this point, you have created an RDS database and an EC2 instance. Now, we will configure the RDS database to allow access to specific entities.

You have to run the below command in your EC2 instance in order to establish the connection with your database.

export MYSQL_HOST=<your-endpoint>

You can find your endpoint by clicking database in the RDS dashboard. Then you have to run the following command.

mysql --user=<user> --password=<password> dbname

This output shows the database is successfully connected to an EC2 instance.

In the MySQL command terminal, you have to run the following commands in order to get all privileges to your account.

CREATE USER 'vishnu' IDENTIFIED BY 'vishnupassword';
GRANT ALL PRIVILEGES ON dbname.* TO vishnu;
FLUSH PRIVILEGES;
Exit

Configuring WordPress on EC2

For Configuring WordPress on EC2 instance, the first step is to configure the webserver, here I am using Apache webserver. For that, you have to run the following commands.

sudo yum install -y httpd

sudo service httpd start

Next step would be download the WordPress application from the internet by using wget command. Run the following code to download the WordPress application.

wget https://wordpress.org/latest.tar.gz
tar -xzf latest.tar.gz

Then we have to do some configuration, for this follow the below steps.

cd wordpress
cp wp-config-sample.php wp-config.php
cd wp-config.php

Go inside the wp-config.php file and enter your credentials (including your password too)

Then, Goto this link and copy all and paste it to replace the existing lines of code.

Next step is to deploy the WordPress application. For that, you have to run the following commands in order to solve the dependencies and deploy WordPress in the webserver.

sudo amazon-linux-extras install -y lamp-mariadb10.2-php7.2 php7.2

sudo cp -r wordpress/* /var/www/html/

sudo service httpd restart

That’s it. You have a live, publicly-accessible WordPress installation using a fully-managed MySQL database on Amazon RDS.

Then if you enter your WordPress instance IP in your browser, you will land your WordPress home page.

After you filled in your credentials, you will get your own homepage.

That’s it. You launched your own application in your own instance and your database is managed by AWS RDS service.

---

Thank you all for your reads. Stay tuned for my next article.

Definition for SQL

Structured query language (SQL) is a programming language for storing and processing information in a relational database. A relational database stores information in tabular form, with rows and columns representing different data attributes and the various relationships between the data values. You can use SQL statements to store, update, remove, search, and retrieve information from the database. You can also use SQL to maintain and optimize database performance.

---

In this article,we are going to discuss how to create a table in a database,insert the values in the table.First start the mariadb server,follow the steps in the article if mariadb is not installed in your system.Refer the Installation guide for mariadb is below link.

https://opendiaryofgowthamg.wordpress.com/2024/02/14/installation-mariadb/

After opening the terminal,we need to know the databases presented in mariadb.So that,use..,

SHOW DATABASES;

It will show the available databases.Next we need to create a database and switch into that new database.Using Capital letters for keywords is a good practice in SQL.

CREATE DATABASE database_name;
USE database_name;

Now,we created a database and switched into it.We need to create a table for this database.

CREATE TABLE table_name (Sno int(3),Name varchar (30),Mobile No int (13));

We created a new table with three columns.
Sno has Integer datatype and it can stores upto 3 integer values (i.e up-to 999).
Name has varchar datatype and it stores up-to 30 Characters.
Mobile No has Integer datatype and stores up-to 13 integer value

DESC table_name;

This command allow us to view the description of that table.Practice is the database name which i was created and testing is the name i given to this table.We will discuss about NULL,Key,Default,Extra are in the later sessions.

This is how we create a simple basic table.Let’s see hoe to insert values to this table.

INSERT INTO table_name values (1,"person_1",1231231231);
INSERT INTO table_name values (2,"person_2",97979797),(3,"person_3",34343434),(4,'person_4',456789123);

First line shows,inserting only a single row data to the table.Whereas,second one shows multi data insertion to the table.We can use either Double Quote (” “) or Single Quote (‘ ‘) to the Character datatype.

Let’s see how to view this table entirely or only a specific column.

SELECT * FROM table_name;
SELECT column_name FROM table_name;

The first image shows the full table contents.
Second image shows only a particular column named “books”.

EXIT;

Exit from mariadb.

We will discuss how to edit,update the table in next article.

That’s it..!

Definition for SQL

Structured query language (SQL) is a programming language for storing and processing information in a relational database. A relational database stores information in tabular form, with rows and columns representing different data attributes and the various relationships between the data values. You can use SQL statements to store, update, remove, search, and retrieve information from the database. You can also use SQL to maintain and optimize database performance.

---

In this article,we are going to discuss how to create a table in a database,insert the values in the table.First start the mariadb server,follow the steps in the article if mariadb is not installed in your system.Refer the Installation guide for mariadb is below link.

https://opendiaryofgowthamg.wordpress.com/2024/02/14/installation-mariadb/

After opening the terminal,we need to know the databases presented in mariadb.So that,use..,

SHOW DATABASES;

It will show the available databases.Next we need to create a database and switch into that new database.Using Capital letters for keywords is a good practice in SQL.

CREATE DATABASE database_name;
USE database_name;

Now,we created a database and switched into it.We need to create a table for this database.

CREATE TABLE table_name (Sno int(3),Name varchar (30),Mobile No int (13));

We created a new table with three columns.
Sno has Integer datatype and it can stores upto 3 integer values (i.e up-to 999).
Name has varchar datatype and it stores up-to 30 Characters.
Mobile No has Integer datatype and stores up-to 13 integer value

DESC table_name;

This command allow us to view the description of that table.Practice is the database name which i was created and testing is the name i given to this table.We will discuss about NULL,Key,Default,Extra are in the later sessions.

This is how we create a simple basic table.Let’s see hoe to insert values to this table.

INSERT INTO table_name values (1,"person_1",1231231231);
INSERT INTO table_name values (2,"person_2",97979797),(3,"person_3",34343434),(4,'person_4',456789123);

First line shows,inserting only a single row data to the table.Whereas,second one shows multi data insertion to the table.We can use either Double Quote (” “) or Single Quote (‘ ‘) to the Character datatype.

Let’s see how to view this table entirely or only a specific column.

SELECT * FROM table_name;
SELECT column_name FROM table_name;

The first image shows the full table contents.
Second image shows only a particular column named “books”.

EXIT;

Exit from mariadb.

We will discuss how to edit,update the table in next article.

That’s it..!