CMSC 461 Database Management Systems(100% Everfree answers)

Database Management System (DBMS) correct answers collection of interrelated data and a set of programs to access those data database correct answers collection of data contains information relevant to an enterprise primary goal of a DBMS correct answers is to provide a way to store and retrieve database information that is convenient and efficient. Drawbacks of File Systems correct answers Data redundancy and inconsistency, Difficulty in accessing data, Data isolation, Integrity problems, Atomicity problems, Concurrent-access anomalies, Security problems file-processing system correct answers stores permanent records in various files, and it needs different application programs to extract records from, and add records to, the appropriate files query correct answers a statement requesting the retrieval of information Levels of Abstraction correct answers physical - describes how a record is stored logical - describes the data stored in the database and the relationships among the data view level - hide and/or modify aspects of data types as seen by various users Schema correct answers logical structure of the database entity correct answers collection of basic objects attributes correct answers Entities are described in a database by a set of relationship correct answers an association among several entities tuple correct answers simply a sequence (or list) of values superkey correct answers a set of one or more attributes that, taken collectively, allow us to identify uniquely a tuple in the relation candidate keys. correct answers minimal superkeys primary key correct answers candidate key that is chosen by the database designer as the principal means of identifying tuples within a relation