What is RDBMS(Relational Database Management System)?

Brief History of RDBMS

Before looking in depth at what is RDBMS, let us look at its history of this. 

• The history of relational database management systems (RDBMS) dates back to the 1970s. 
   
• The concept of a relational database was first proposed by Edgar F. Codd in 1970, while he was working at IBM. 
   
• Codd's proposal was for a database management system that used a relational model for data organization, rather than the hierarchical and network models that were commonly used at the time. 
   
• In the years that followed, various researchers and companies developed their own implementations of relational database systems. The first commercial RDBMS was released by Relational Software (later known as Oracle) in 1979. 
   
• Other early RDBMSs included IBM's Information Management System (IMS) and System R, which were developed by IBM as a research project. 
   
• Over the next few decades, RDBMSs became the dominant type of database management system and are still widely used today. 

Key features of RDBMS

There are several key features of RDBMS, which are as follows:

• RDBMS provides atomicity so that the data keeps accurate.
   
• RDBMS also provides consistency so that the database remains constant throughout the transaction.
   
• The data in RDBMS is durable, which means you can recover the data in case a transaction fails.
   
• All the data is stored in the RDBMS table in the form of rows and columns.
   
• Indexes are created by the RDBMS so that the data retrieval can be faster.
   
• DBMS also provides a feature of virtual table creation (views) so the sensitive data can be stored, and then the queries can be applied to them.

The Relational Model

The relational model is a robust and adaptable data model that is utilised by a wide range of organisations. The most popular kind of database, relational databases, are built on top of it.

Here are a few examples of real-world applications of the relational model:

• The relational model can be used to hold information on employees, such as their name, job title, and income, in a human resources system.
   
• Customers' names, addresses, phone numbers, and purchase history may all be stored in a customer relationship management (CRM) system using the relational paradigm.
   
• A financial system may use the relational model to record information about transactions, including the sum of money transferred, the transaction date, and the account numbers involved.

An effective technique for managing and organising data is the relational model. It is utilised by a wide range of organisations to successfully store and retrieve data.

Working of RDBMS

The data in the RDBMS is stored in a table in the form of rows and columns, where each table has a unique primary key. Let's understand what are the rows and columns first.

Rows: It is a horizontal entity where the information about a specific entry is stored.

Columns: It is a vertical entity where the specific entry is stored of the information provided in the rows.

So whenever a user executes a query, RDBMS shows the result for the specific query. Here is an example which will help you to understand how RDBMS works. Assume you are the teacher of the class who wants to store the subject marks of every student in the class. Then this task can be done with the help of RDBMS by just creating a table of a few rows and columns of the teacher's choice. Here's the table that a teacher can create to organize and store the data:

In the above table, there are three students for whom the teacher created three rows where every student is an entity. There are four columns for the properties of the rows created for each student there are different properties created. We can execute the queries based on these rows and columns, such as creating, updating, reading, and deleting the specific row or column.

What are Tables/Relations in RDBMS?

In a relational database management system (RDBMS), tables, also known as relations, are used to store data. 

• A table consists of rows (also known as records or tuples) and columns (also known as fields or attributes). 
   
• Each column in a table represents a specific attribute or piece of information, and each row represents a single instance of that data. 
   
• For example, a table called "EMPLOYEES" might have columns for "ID", "NAME", "ADDRESS", and "SALARY", and each row would represent a different employee with their corresponding information in each column.

• Tables are related to each other through the use of keys. 
   
• A primary key is a column or set of columns that uniquely identify each row in a table, and is used to establish relationships between tables. 
   
• A foreign key is a column or set of columns in one table that refers to the primary key of another table. 
   
• By using these relationships, the data in the tables can be related to each other and queried in a way that is efficient and maintainable.

What is a Row/Record?

In a relational database, a row, also known as a record, is a data collection representing a single item or unit of information. Each row in a table contains data for a specific entity, such as a customer, an order, or a product. 

• For example, in a table called "Customers", each row represents a single customer, and it would contain information such as the customer's name, address, and phone number. 
   
• Similarly, in a table called "Orders", each row represents a single order, and it would contain information such as the order date, the customer who placed the order, and the total cost. 
   
• In a table, the data of each row is stored in columns, and each column represents a specific piece of information about the entity that the table represents. The columns are fields, attributes, or properties, and each column has a specific data type.

For example, in a Customers table, a column might be "FirstName" with a data type of varchar, and another column might be "LastName" with the same data type, and so on.

What is a Column/Attribute?

In a relational database, a column, also known as an attribute or field, represents a specific piece of information about the entity that a table represents. Each column in a table corresponds to a specific data type, such as integer, string, or date. 

• For example, in a "Customers" table, a column might be "FirstName" with a data type of varchar, and another column might be "LastName" with the same data type, and so on. 
   
• In an "Orders" table, a column might be "OrderDate" with a data type of date, and another column might be "TotalCost" with a data type of decimal.

Each row in a table contains a value for each column, and each column has a unique name within the table. The name of the column is used to refer to the column when querying the database.

What is a Data Item/Cell?

In a relational database, a data item, also known as a cell, is the basic unit of data storage. It is the intersection of a row and a column in a table. Each data item, or cell, contains a single value that corresponds to a specific piece of information about the entity that the table represents. 

• For example, in a "Customers" table, the data item in the cell located at the intersection of the first row and the "FirstName" column would contain the first name of the customer represented by that row. 
   
• Similarly, in an "Orders" table, the data item in the cell located at the intersection of the second row and the "TotalCost" column would contain the total cost of the order represented by that row. 
   
• The value in each data item, or cell, must conform to the data type of the column in which it is located. 
   
• For example, if a column is defined as an integer data type, the data item in that column must contain an integer value.

What is the Degree of a Table?

The degree of a table in a relational database management system (RDBMS) refers to the number of columns or fields in the table. It is also sometimes referred to as the "arity" of the table. 

• For example, in the table "EMPLOYEES" that is described earlier, the degree of the table would be 4, because it has 4 columns (ID, NAME, ADDRESS, and SALARY).
   
• It is also important to note that the degree of a table can also be referred to as the number of attributes in the table. 
   
• The degree of a table can be important to consider when designing a relational database, as it can affect the performance of the database and the ability to retrieve and manipulate the data. 
   
• A table with a high degree may have more columns than necessary, which could lead to slower performance and increased storage requirements.

What is Cardinality of a Table?

The cardinality of a table in a relational Database management system (RDBMS) refers to the number of rows or tuples in the table. It is also sometimes referred to as the "population" of the table. 

• For example, in the table "EMPLOYEES" that I described earlier, the cardinality of the table would be 3, because it has 3 rows (or tuples), each representing a different employee. 
   
• The cardinality of a table can be important to consider when designing a relational database, as it can affect the performance of the database and the ability to retrieve and manipulate the data. 
   
• A table with a high cardinality may have more rows than necessary, which could lead to slower performance and increased storage requirements. 

Example of RDBMS

A relational database is a collection of tables related to each other through common fields. Each table in a relational database represents a specific entity, such as customers, orders, or products. For example, consider a simple database for a retail store with the following tables:

Customers: 
This table contains information about the store's customers, such as their names, address, and phone number. The table might have the following fields:

• CustomerID (Primary Key)
• FirstName
• LastName
• Address
• PhoneNumber

Orders: 
This table contains information about the store's orders, such as the order date, the customer who placed the order, and the total cost. The table might have the following fields:

• OrderID (Primary Key)
• OrderDate
• CustomerID (Foreign Key referencing the Customer table)
• TotalCost

Products: 
This table contains information about the store's products, such as the product name, price, and quantity in stock. The table might have the following fields:

• ProductID (Primary Key)
• ProductName
• Price
• QuantityInStock

In this example, the Customers, Orders, and Products tables are related to each other through the common fields (CustomerID, OrderID, and ProductID) which are the primary keys of their respective tables. By using SQL statements, we can query the data in these tables to obtain meaningful information, such as the names of customers who have placed orders, the total cost of all orders placed by a specific customer, or the products that are currently out of stock.

Also see, Recursive Relationship in DBMS

Advantages of RDBMS

Relational Database Management Systems (RDBMS) are widely used due to their many benefits, which include:

1. Data Integrity

RDBMS provides a way to maintain data integrity by enforcing rules and constraints on data, such as unique values and referential integrity, to ensure that the data is accurate and consistent.

2. Data Consistency

RDBMS provides a way to maintain data consistency by using transactions and locking mechanisms to ensure that multiple users do not modify data simultaneously.

3. Data Security

RDBMS provides a way to protect data by controlling its access, using security mechanisms such as authentication and authorization.

4. Data Scalability

RDBMS provides a way to scale data by allowing the addition of more disk space, memory, and processors as needed to handle increasing amounts of data.

5. Flexibility

RDBMS provides a way to access and manipulate data in a flexible and powerful way, using SQL (Structured Query Language) and other query languages, which allows users to create, read, update, and delete data.

Uses of RDBMS

Relational database management systems (RDBMS) are used to store and manage data in a structured way. They are commonly used for a wide variety of applications, including

• Businesses and organizations that use RDBMS to store and manage information such as customer data, sales data, financial data, and more.
   
• Online retailers use RDBMS to store and manage information about products, inventory, orders, and customers.
   
• Social media platforms use RDBMS to store and manage information about users, posts, and interactions.
   
• Banks and other financial institutions use RDBMS to store and manage financial transactions and account information.
   
• Healthcare organizations use RDBMS to store and manage patient medical records, test results, and other medical information.
   
• Government agencies use RDBMS to store and manage information such as voter records, tax records, and other official data.
   
• Educational institutions use RDBMS to store and manage student records, course schedules, and other information.

Difference between DBMS and RDBMS

A Database Management System (DBMS) is a software system used to manage and organize data in a database. A Relational Database Management System (RDBMS) is a specific type of DBMS that uses a relational model to organize and store data. There are several key differences between DBMS and RDBMS:

RDBMS is a type of DBMS that uses a relational model, enforces data integrity, uses SQL as a query language, and supports concurrent access.

Also Read, Apache Spark

Frequently Asked Questions

What is a RDBMS give example?

A Relational Database Management System (RDBMS) is a type of database management system that stores data in the form of tables and uses a relational model to organize and manage data.

What is RDBMS vs DBMS?

The RDBMS stands for Relational Database Management System, and DBMS stands for Database Management System. The data is stored in the RDBMS as a table, whereas in the DBMS, it is stored as a file.

What is RDBMS's benefit?

RDBMS provides data integrity, consistency, security, scalability, flexibility, and interoperability, which makes them a popular choice for storing and managing data.

What is RDBMS Acid Property?

ACID properties are Atomicity, Consistency, Isolation, and Durability. They ensure that a transaction is treated as a single, indivisible unit of work, maintain data integrity, ensure concurrency, and ensure that the effects of a transaction are permanent.

Conclusion

In this article, we have discussed what is RDBMS, the example, and its benefits. The most popular kind of database management system is an RDBMS. The relational model, a method of organising data in tables, is the foundation upon which RDBMSs are built. A relational database's tables each have a distinct name and several columns. Each row represents one data record in a table. Suppose you want to learn about  DBMS and SQL. In that case, you can read the below-mentioned articles:

• Joins in dbms
• Create Table in SQL
• SQL Expressions
• Cardinality In DBMS
• multiple granularity in dbms
• Aggregation in DBMS

Happy Learning!