Database system concepts Upplaga 2

This is a major revision of the bestselling Database Systems text for undergraduate courses offered in departments of Computer Science, Computer Engineering and Electrical Engineering.Special features a focus on network and hierarchical models giving increased emphasis to the relational model; an intuitive, rather than formal approach giving students a headstart on intuitive thinking; many examples, problems, and cases from the real world of computers. New to this edition expanded coverage of SQL and QBE; a new chapter on Integrity Constraints; improved relational algebra and relational calculus notation that simplifies the discussion of such difficult concepts as safety of queries; coverage of new directions in a completely revised Chapter 14, namely object-oriented databases, datalog, and long duration transactions.