Definition of Relational Database
What is a relational database? A relational database (RDBMS) is a software system for storing, managing, and retrieving data. It stores data in relational tables that consist of rows and columns, where each row represents a record and each column represents an attribute.
These relational tables are related to each other by keys (primary and foreign keys), forming a complex data network structure.
Historical Background of Relational Database
The concept of a relational database was first proposed by Edgar Codd of IBM in 1970. Codd’s theory of relational algebra laid the foundation for the design of relational databases.
With the development of technology, in 1974, the first commercial relational database management system, System R, was launched by IBM. System R manages and queries relational databases by using SQL (Structured Query Language). Since then, relational database management systems have become widely used around the world.
Structure of A Relational Database
A relational database consists of the following major components:
- Database: A physical container for storing data, including relational tables, views, indexes, etc.
- Relational table: A data structure consisting of rows and columns for storing data.
- Views: virtual tables generated based on query results of relational tables, providing an abstraction of the underlying data.
- Index: A data structure used to accelerate data queries. With indexes, the database can quickly locate rows of data that satisfy specific conditions.
- Trigger: A special type of stored procedure that is automatically triggered to execute when a specific event (e.g., an insert, update, or delete operation) occurs.
- Stored Procedure: Pre-compiled SQL code used to encapsulate complex business logic to improve the efficiency of data processing.
- User Rights and Security: In order to ensure data security, relational database management systems usually provide user rights management and data encryption features.
Principles of Relational Databases
You can also have a deeper knowledge of what is a relational database through its principles. Relational databases are based on the theory of relational algebra for data manipulation and management. Relational algebra is an abstract mathematical model based on set operations to describe operations on relationships.
In relational algebra, common operations include Selection, Projection, Join, Cartesian Product and so on. These operations can be used to realize operations such as querying, inserting, updating and deleting data.
In addition, relational databases follow the ACID principles (Atomicity, Consistency, Isolation and Durability). This means that the database is able to maintain data integrity and consistency in case of concurrent access by multiple users or in case of failure.
Benefits of Relational Databases
A relational database can store data in a structured way, making it easier to manage and query. It has integrity constraints that can ensure the accuracy and consistency of data.
In addition, relational databases support transaction processing and can realize data rollback and database recovery. It is able to use SQL language for querying and has efficient query performance.
The relational database can also be expanded by adding servers and hard disks, etc., and has good scalability.
What is A Relational Database: Term Comparison
Relational Database vs Relational Database Management System
Relational Database (RDBMS) is a kind of database that stores data organized according to a relational model. Relational Database Management System (Relational Database Management System, RDBMS) is used to manage the relational database software system.
Therefore, relational database and RDBMS are closely related concepts.
Relational Database vs Non-Relational Database
A non-relational database (NoSQL) is a database that is not based on a relational model and usually uses key-value pairs, documents, column families, etc. to organize and store data.
Compared to relational databases, non-relational databases are more flexible and scalable, but may not be as good as relational databases in terms of consistency and query performance.
Common non-relational databases include MongoDB, Cassandra, Redis, etc.
Conclusion
Relational database is an important technology widely used in various information systems. It takes relational table as the basic data structure, manages and queries through SQL language, and follows the ACID principle to ensure data consistency and integrity.
The above content is a more comprehensive overview of what is a relational database and introduction, understanding and mastering the relevant knowledge of relational database for the development and management of various types of information systems is essential.