All You Need to Know About Relational Database Management Systems (RDBMSs)

By |2020-01-01T10:05:39+00:00January 1st, 2020|

A Relational Database Management System (RDBMS) provides a foundation for numerous apps and services. Technologically, RDBMS are considered primeval. However, strong theoretical foundation of this technology has kept it pertinent in a volatile industry. This is why even non-relational databases include RDBMS-like features, such as the SQL interface in Hadoop.

In this article, we’ll cover what an RDBMS is and how it works. Next, we’ll see how it is different from a DBMS. Lastly, we’ll look at some of its key advantages.

What is a Relational Database Management System?

According to E. F. Codd’s relational model, an RDBMS allows users to construct, update, manage, and interact with a relational database, which stores data in a tabular form.

Today, various businesses use relational databases instead of flat files or hierarchical databases for storing enterprise data. This is because a relational database can handle a wide range of data formats and process queries efficiently. Moreover, it organizes data into tables that can be linked internally depending on common data. This allows the user to retrieve one or more tables easily with just one query. On the other hand, a flat file stores data in a single table structure, which makes it less efficient and consumes more space and memory.

Most commercially available RDBMSs today use Structured Query Language (SQL) to access the database. RDBMS structures are most commonly used to perform CRUD (create, read, update and delete) operations, that are critical in supporting consistent data management.

Differences Between RDBMS and DBMS

An RDBMS is an advanced version of a DBMS. Unlike a DBMS that manages databases present on the computer network and hard disks, an RDBMS helps maintain the relationships between its tables.

The following are some of the main differences between an RDBMS and a DBMS:

  • Number of operators: A DBMS allows only a single operator at a time, whereas multiple users can operate an RDBMS concurrently. This is because an RDBMS uses intricate algorithms that enables several users to simultaneously access the database while preserving data integrity.
  • Hardware and software needs: A DBMS utilizes less resources for data storage and retrieval as compared to an RDBMS. This is because the latter is more complex due to its multi-table structure and cross-referencing capability, making it costlier than a DBMS. RDBMSs are also generally used for enterprise-class applications while DBMSs are more commonly utilized for smaller, purpose-specific applications.
  • Data modification: Altering data in a DBMS is quite difficult, whereas you can easily modify data in an RDBMS using an SQL query. Thus, programmers can change/access multiple data elements simultaneously. This is one of the reasons why an RDBMS is more efficient than a DBMS.
  • Data volume: A DBMS is more suitable for handling low data volume, whereas an RDBMS can handle even large data volumes.
  • Keys and Indexes: A DBMS doesn’t involve keys and indexes, whereas an RDBMS specifies relationship between data elements via keys and indexes.
  • Data consistency: As a DBMS does not follow the ACID (Atomicity, Consistency, Isolation, and Durability) model, the data stored can have inconsistencies. Whereas, an RDBMS follows the ACID model, which makes it structured and consistent.
  • Database structure: A DBMS stores data in a hierarchical structure, while an RDBMS stores data in tables.
  • Data fetching speed: In a DBMS, the data fetching process is quite slow especially when data is complex and the volume is large. This is because each of the data elements must be fetched individually. In an RDBMS, data is fetched at a faster pace because of the relational approach. Plus, SQL facilitates quicker data retrieval in an RDBMS.
  • Distributed databases: A DBMS doesn’t support distributed databases, whereas an RDBMS offers full support for distributed databases.
  • Client server architecture: Unlike a DBMS, an RDBMS supports client-server architecture.

How Does an RDBMS Work?

Relational databases use several tables, and every table is arranged into rows (also called records or tuples) and columns (also known as fields or attributes).

Tables in the relational database can be connected in different ways, such as:

  • A record in one table could be related to another record in a different table (1:1 relationship)
  • A record in one table may be related to several records in other table (1:M relationship)
  • Several table records could be linked to multiple records in a different table (M:N relationship)

However, before tables are created, an RDBMS must ensure that:

  • Each table has a unique primary key, which has no null values.
  • The foreign key, which is used to relate 2 tables, is preserved in one table and refers to the primary key of another table.
  • No column has a null value (empty cell).

Here’s an example of a table in a relational database.

relational database management system

Source: Guru99

An RDBMS usually comes with data dictionaries and collections of metadata, which are beneficial in data management. A data dictionary defines the data objects of every user within the database. As a result, it helps users identify all the objects which exist in the database as well as who can access it.

For instance, it’s humanly impossible to remember all the tables stored in a huge database. Now if you want to search for a specific table, such as Products, you can use data dictionary to look up for all the tables named Products. From the list of resulting tables, you can identify your required one.

Advantages of RDBMS

A relational database management system offers a methodical view of data, which helps businesses improve their decision-making processes by enhancing different areas, such as:

Enhanced Data Security

The authorization and access control features in an RDBMS support advanced encryption and decryption, enabling database administrators to manage access to the stored data. This offers significant benefits in terms of security. Operators can modify access to the database tables and even limit the data that’s available to others. This makes RDBMSs an ideal data storage solution for businesses where the higher management needs to control data access for workers and clients.

Retain Data Consistency

In an RDBMS, it is easier to add new data or modify existing tables while maintaining data consistency with the existing format. This is mainly because an RDBMS is ACID-compliant.

Better Flexibility and Scalability

An RDBMS offers more flexibility when it comes to updating data as the modifications only have to be made once. For instance, updating the details in the main table will automatically update the relevant files and save you the trouble of changing several files one by one. Plus, each table can be altered independently without disturbing the others. This makes relational databases scalable for growing data volumes.

Easy Maintenance

The maintenance features in relational databases enables users to easily test, regulate, fix, and back-up data. This is because an RDBMS includes automation tools that systematize these tasks.

Reduced Risk of Errors

In a relational database, you can easily check for errors against the data in different records. As each data item is stored at a single location, there’s no possibility of older versions blurring the picture.


Over time, RDBMSs have evolved to provide increasingly advanced levels of query optimization and sophisticated plugins for enterprise developers. As a result, these systems have become essential for a variety of enterprise applications. They also serve as a focal point in numerous applications, such as reporting, analytics, and data warehousing.