Relational Query Languages Procedural versus non-procedural,or declarative ■“Pure”languages: ·Relational algebra Tuple relational calculus Domain relational calculus The above 3 pure languages are equivalent in computing power We will concentrate in this chapter on relational algebra Not Turing-machine equivalent Consists of 6 basic operations Database System Concepts-7th Edition 2.10 ©Silberscha乜，Korth and SudarshanDatabase System Concepts - 7 2.10 ©Silberschatz, Korth and Sudarshan th Edition Relational Query Languages ▪ Procedural versus non-procedural, or declarative ▪ “Pure” languages: • Relational algebra • Tuple relational calculus • Domain relational calculus ▪ The above 3 pure languages are equivalent in computing power ▪ We will concentrate in this chapter on relational algebra • Not Turing-machine equivalent • Consists of 6 basic operations