Relational Calculus
Relational calculus is a formal, non-procedural query language used in database theory to specify what data to retrieve from a relational database, without describing how to retrieve it. It serves as the theoretical foundation for relational algebra and SQL, focusing on declarative expressions based on predicate logic. There are two main variants: tuple relational calculus (TRC) and domain relational calculus (DRC), which differ in how they reference database elements.
Developers should learn relational calculus to understand the mathematical underpinnings of relational databases and SQL, which is essential for database design, query optimization, and advanced data manipulation. It is particularly useful for academic study, database theory research, and roles involving complex query formulation or database system implementation, as it helps in reasoning about query correctness and efficiency.