The relational model emphasizes data relationships from "summary" of SQL and Relational Theory by C. Date
The relational model, as articulated in the classic work by E. F. Codd, is based on the idea that data can be organized into tables, with each table representing a relation. A relation, in turn, is essentially a set of rows, where each row corresponds to a particular entity or object, and each column corresponds to an attribute or property of that entity. One of the key features of the relational model is its emphasis on the relationships between different entities. These relationships are represented by the way in which the tables are structured and linked together through keys. By explicitly defining these relationships, the relational model helps to ensure the integrity and consistency of the data. For example, consider a database that tracks information about employees and the departments they work in. In this database, there would likely be two tables: one for employees and one for departments. The tables would be linked together through a key, such as an employee ID, which would appear in both tables. This relational approach allows for complex queries that can span multiple tables and retrieve information based on the relationships between entities. For instance, a query could be written to find all employees who work in a particular department, or to calculate the average salary of employees in each department.- The relational model provides a way to represent the real-world relationships between different entities in a structured and logical manner. By emphasizing these relationships, the model enables data to be organized and manipulated in a way that reflects the inherent connections between entities.
