tailieunhanh - Lecture Database system concepts (6/e): Appendix C - Silberschatz, Korth, Sudarshan

Appendix C - Other relational languages, first presents the relational query language Query-by-Example (QBE), which was designed to be used by non-programmers. In QBE, queries look like a collection of tables containing an example of data to be retrieved. The graphical query language of Microsoft Access, which is based on QBE, is presented next, followed by the Datalog language, which has a syntax modeled after the logic-programming language Prolog. | Appendix C: Other Relational Languages Database System Concepts, 6th Ed. ©Silberschatz, Korth and Sudarshan See for conditions on re-use Appendix C: Other Relational Languages Query-by-Example (QBE) Access Datalog Database System Concepts - 6th Edition ©Silberschatz, Korth and Sudarshan Query-by-Example (QBE) Basic Structure Queries on One Relation Queries on Several Relations The Condition Box The Result Relation Ordering the Display of Tuples Aggregate Operations Modification of the Database Database System Concepts - 6th Edition ©Silberschatz, Korth and Sudarshan QBE — Basic Structure A graphical query language which is based (roughly) on the domain relational calculus Two dimensional syntax – system creates templates of relations that are requested by users Queries are expressed “by example” Database System Concepts - 6th Edition ©Silberschatz, Korth and Sudarshan QBE Skeleton Tables for the Bank Example Database System Concepts - 6th Edition ©Silberschatz, Korth and .