What is the main advantage of using a relational database?

The main advantage of using a relational database lies in its ability to ensure data integrity and facilitate complex queries. Relational databases are designed based on structured query language (SQL), which allows users to perform sophisticated queries involving multiple tables through joins and other operations. This capability supports the development of complex data relationships and enables users to retrieve precise information with minimal effort.

Data integrity is another significant aspect of relational databases, where the structure enforces rules such as primary keys, foreign keys, and constraints. These elements help prevent data anomalies and maintain consistency within the database. For instance, a foreign key constraint ensures that only valid, pre-existing entries can be linked across tables, thereby preserving the accuracy of relationships within the data.

While ease of use for non-technical users can be a feature of some relational database interfaces, the fundamental strengths of these systems lie in their ability to handle data integrity and complex querying. The other options focus on cost and compatibility with older systems, which are not inherent advantages of relational databases but might pertain to specific implementations or use cases.