A relational database is a database model in which information is stored in tables consisting of rows and columns, with defined relationships between those tables. A Relational Database Management System, commonly abbreviated as RDBMS, is the software used to create, query, update and manage relational databases. The relational model was introduced through research published by computer scientist Edgar F. Codd in 1970. It later became one of the foundations of modern database management.
Information in a relational database is stored within structured tables. Each table generally represents a particular entity, such as a customer, product, employee or order. Each row represents an individual record, while columns describe the attributes of that record. For example, a customer table may include columns for name, telephone number, email address and location, with each row containing information about a separate customer.
A primary key is generally used to identify each row uniquely. A customer number in a customer table may serve as the primary key that distinguishes one customer from another. Relationships between tables are commonly created through foreign keys. For example, a customer number stored in an order table can connect each order to the relevant customer record.
The relational model enables information to be stored systematically and connected meaningfully across separate tables. Customer, order and product information may be stored independently but queried together through their key relationships. This structure can reduce unnecessary data duplication and support more consistent record management. When the model is designed correctly, insert, update and deletion operations can also be managed more reliably.
The most widely used query language in relational database management systems is SQL. The abbreviation stands for Structured Query Language. SQL can be used to retrieve information, insert new records, update existing values and delete selected data. It can also be used to manage tables, relationships, permissions and data integrity rules.
Relational databases are used in finance, e-commerce, healthcare, telecommunications, public services and enterprise resource management. They are particularly suitable for structured information such as customer records, orders, payment transactions, inventory data and employee details. Organisations of different sizes can use these systems according to their operational requirements. MySQL, PostgreSQL, Microsoft SQL Server and Oracle Database are common examples of RDBMS platforms.
One of the main advantages of relational database systems is their support for data integrity. Primary keys, foreign keys, data types and constraints can limit the creation of invalid or inconsistent records. Access controls can determine which users are authorised to view or modify particular tables. Backup, transaction management and recovery capabilities can also help reduce the risk of data loss.
Relational databases can be expanded by adding new columns, tables and relationships, but significant structural changes must be planned carefully. Major modifications may affect existing applications, queries and reports. Alternative approaches such as NoSQL may be more suitable for highly variable, rapidly changing or unstructured datasets. Database selection should therefore reflect the structure of the data, transaction requirements, scalability needs and the overall application design.
