Database System – 3rd theory class : Formal Relational Query Languages 20/03/16

Formal Relational Query Languages (形式化查询语言) Query Language : language in which users request information from the database Categories of languages : procedural (过程性) Relational Algebra (关系代数) non-procedural (非过程性) Turple Kelational (元组关系演算) / Domain Relational Calculus (域关系演算) ” Pure language “ Rela