Computer Science 6360 Database Design Instructor Weili Wu Email weiliwu utdallas edu 972 883 2194 Office Hours Wednesday 3 45pm 5 00pm Online Class web page http www utdallas edu weiliwu CS6360 S2022 CS6 360 S2022 htm available on eLearning Assignments due on Mondays T A TBD Prerequisite CS5343 Algorithm Analysis and Data Structure 2 Textbooks Required Elmasri and Navathe Fundamentals of Database Systems 6th Edition Addison Wesley ISBN 10 0 136 08620 9 ISBN 13 978 0 136 08620 8 3 Grading 1 3 2 5 3 7 15 of grade Assignments Project 15 Midterm 30 of grade Final 40 of grade Conditions for passing the class Submit all HWs and Project Scoring 50 on final exam 4 Assignments Submission Submission Policy HWs must be submitted via eLearning on specified due date Mondays of designated weeks The project must be submitted via eLearning on due date Late hws also should be submitted via eLearning postscript pdf text or MS Word doc files Late HWs penalty 1 day 30 will be deducted 2 days 70 will be deducted count weekend days 3 days no credit 5 Comment This class is very interesting and useful work regularly Good luck 6 Schedule View the candidate course schedule on course syllabus and eLearning Check update via eLaening 7 Overview of Databases and Basic Concepts Chapter 1 2 8 What is a Database Collection of data central to some enterprise Data Known facts that can be recorded and have an implicit meaning Essential to operation of enterprise Contains the only record of enterprise activity An asset in its own right Historical data can guide enterprise strategy Of interest to other enterprises Database is persistent Mini world Some part of the real world about which data is stored in a database For example student grades and transcripts at a university 9 What is a Database Management System A Database Management System DBMS is a program software package that manages a database Supports a high level access language e g SQL Application describes database accesses using that language DBMS interprets statements of language to perform requested database access 10 What is a Database Management System Cont Supports concurrent access to very large amounts of data Example bank and its ATM machines Supports secure atomic access to very large amounts of data Contrast two people editing the same UNIX file with the problem if two people deduct money from the same account via ATM machines at the same time new balance is wrong whichever writes last 11 Database System The DBMS software together with the data itself Sometimes the applications are also included 12 The DBMS Marketplace Relational DBMS companies Oracle Sybase are among the largest software companies in the world IBM offers its relational DB2 system With IMS a nonrelational system IBM is by some accounts the largest DBMS vendor in the world Microsoft offers SQL Server plus Microsoft Access for the cheap DBMS on the desktop answered by lite systems from other competitors Relational companies also challenged by object oriented DB companies But countered with object relational systems which retain the relational core while allowing type extension as in OO systems 13 An Example of Database Mini world for the example Part of a UNIVERSITY environment Some mini world entities STUDENTs ID Name SecId CourseNum COURSEs SECTIONs of COURSEs DEPARTMENTs INSTRUCTORs 14 Some mini world relationships SECTIONs are of specific COURSEs STUDENTs take SECTIONs COURSEs have prerequisite COURSEs INSTRUCTORs teach SECTIONs COURSEs are offered by DEPARTMENTs STUDENTs major in DEPARTMENTs The above could be expressed in the ENTITY RELATIONSHIP ER data model 15 16 Benefits of Using DBMS Controlling redundancy in data storage and in development and maintenance efforts Sharing of data among multiple users Restricting unauthorized access to data Providing multiple interfaces to different classes of users Representing complex relationships among data Enforcing integrity constraints on the database Providing backup and recovery services 17 Benefits of Using DBMS cont Potential for enforcing standards Flexibility to change data structures Reduced application development time Availability of up to date information Economies of scale 18 19 When not to use a DBMS Main costs of using a DBMS High initial investment and possible need for additional hardware Overhead for providing generality security recovery integrity and concurrency control When a DBMS may be unnecessary simple well defined and not expected to change If access to data by multiple users is not required When no DBMS may suffice DB system can not handle the complexity of data Not support special operations 20 Three Aspects to Studying DBMS s 1 Modeling and design of databases Allows exploration of issues before committing to an implementation 2 Programming queries and DB operations like update SQL intergalactic data speak 3 DBMS implementation Query processing and optimization Concurrency control Transaction 21 Main Characteristics of Database Technology Self contained nature of a db system A DBMS catalog stores the description of the database The description is called meta data This allows the DBMS software to work with different databases Insulation between programs and data Called program data independence Allows changing data storage structures and operations without having to change the DBMS access programs Data Abstraction A data model is used to hide storage details and present the users with a conceptual view of the database Support of multiple views of the data Each user may see a different view of the database which describes only the data of interest to that user Virtual data not actual stored Sharing of data and multiuser transX processing Concurrency control 22 23 Data Model Data Model database A set of concepts to describe the structure of a certain constraints data types relationships that the database should obey Provides abstraction Hide low level storage details Data Model Operations Operations for specifying database retrievals and updates by referring to the concepts of the data model 24 Categories of data models Conceptual data models high level semantic Provide concepts that are close to the way many users perceive data Also called entity based or object based data models Physical data models low level internal Provide concepts that describe details of how data is stored in the computer Implementation record oriented data models Provide concepts that fall between the above two balancing user views
View Full Document
Unlocking...