How is a relational database defined?

A relational database is defined as a database composed of tables with defined relationships because it organizes data into structured formats that can easily be accessed, managed, and updated. Each table, also known as a relation, consists of rows and columns where each row represents a single record and each column represents an attribute of that record. The relationships between tables allow for complex queries and data integrity through the use of keys, such as primary and foreign keys.

This structure enables efficient data retrieval and manipulation through structured query language (SQL), which provides a powerful means to interact with the data in a systematic way. The integrity constraints within relational databases ensure that relationships between data are maintained accurately, thus preserving the accuracy and reliability of the information stored.

In contrast, databases based on key-value pairs lack the structured relationship between data entities. Hierarchical databases, while also organized, reflect tree-like structures that do not provide the flexibility found in relational databases. Databases designed for unstructured data typically store data in formats that do not conform to a predefined schema, which is fundamentally different from the organized tabular structure of relational databases.