Concepts of Database Management, Fifth Edition Chapter 1: Introduction to Database Management

2 Objectives u Why study database management? u Introduce Premiere Products, the company that is used as the basis for many of the examples throughout the text u Introduce basic database terminology u Describe database management systems u Explain the advantages and disadvantages of database processing u Introduce Henry Books, the company that is used in the case that runs throughout the text

3 Why manage data? u Changing view of data u Higher costs of lost data u Encouragement of “team problem- solving” u Flexible reporting u Integrating it into decision-making better

4 Background Info u DBMS software $25B/year industry u Networked DBMS growing fastest u DB research underpins l communication systems l Enterprise applications l multimedia l Internet l scientific applications

5 Data Management Tasks designing the file or database structure entering the data updating data by adding, changing, or deleting sorting the data searching through the data for a record or group of records obtaining screen or printed output Common tasks for flat files and databases are:

6 Approaches to Data Management include: Custom Program Approach File Processing System Approach Database Management System Approach

7 Contrasting Database and File System Designs

8 Problems associated with file processing systems u Application/Program dependence u Data is separate and isolated u Data reduplication u Multiple formats; hard to share data across applications.

9 Database Management Systems Operating System Database Management System Application Programs Operating System Database Management System Application Programs Databases Data Dictionary Database Management

10 Disadvantages of DBMS Approach u Cost u Size u Complexity u Additional Hardware Requirements u Higher Impact of Failure u Recovery more difficult

11 Major Types of Databases Database Server Database Server External Databases End User Workstation Operational Databases Analytical Databases Data Warehouse Databases End User Databases Distributed Databases

12 Database Management Systems u Program(s) through which users interact with database u Popular DBMSs include l Access l Oracle l DB2 l SQL Server u Premiere Products decides to use Access

13 DBMS Classifications u Platform l Stand alone l Network l Mainframe u Organizational Level l `Individual l Workgroup l Enterprise-wide (ex. SAP use of Oracle) u Data Model Supported l Hierarchical l Network l Relational l Object-Oriented

14 Database Models Hierarchical Network Relational Object-oriented details follow

15 Logical Data Elements Personnel Database Employee Record 2 Employee Record 1 Employee Record 3 Employee Record 4 NameSSSalaryNameSSSalaryNameSSSalaryNameSSSalary Data Payroll File Benefits File

16 Database Structures Dept A B C EmpnoDept 1A 2B 3C Relational Structure Network Structure Hierarchical Structure

17 Premiere Products u Distributor of appliances, house wares, and sporting goods u Uses spreadsheet software to maintain important data u Recent growth has made spreadsheet approach problematic

18 Figure 1.1: Sample Orders Spreadsheet

19 Problems Using Spreadsheet u Redundancy l Duplication of data or the storing of the same data in more than one place l Occurs when the same information is stored in more than one place u Difficulty accessing data u Limited security u Size limitations

20 Premiere Products Required Information u Sales Reps l Sales rep number, last name, first name, address, total commission, commission rate u Customers l Customer number, name, address, current balance, credit limit, customer sales rep u Parts Inventory l Part number, description, number units on hand, item class, warehouse number, unit price

21 Figure 1.2: Premiere Products Sample Order

22 Premiere Products Customer Order u Order l Order number, order date, customer number u Order line l Order number, part number, number units ordered, unit price u Overall order total l Not stored since it can be calculated

23 Database Background u Database l Structure that can store information about u Multiple types of entities u Attributes of those entities u Relationships among entities u Entity l Person, place, thing, or event l Premiere Products has sales reps, customers, orders, and parts

24 Database Background (con’t) u Attribute l Property of an entity l Customer has name, street, city, et cetera l May also be called a field or column

25 Figure 1.3: Entities and Attributes

26 Database Background (con’t.) u Relationship l Association between entities l One-to-many relationship - rep is related to many customers l Customer is related to a single rep u Data file l File used to store data l Computer counterpart to ordinary paper file

27 Figure 1.4: One-to-Many Relationship

28 Figure 1.5: Rep and Customer Tables

29 Figure 1.5: Orders and OrderLine Tables (con’t.)

30 Figure 1.5: Part Table (con’t.)

31 Figure 1.6: Alternative Orders Table

32 Entity-relationship Diagram u Visual way to represent a database l Rectangles represent entities l Lines represent relationships between connected entities

33 Figure 1.7: E-R Diagram

34 Figure 1.8 and 1.9: Using DBMSs in Different Ways

35 Building a Database u Database design determines the structure of a database u Design entered into DBMS during construction l Tables – stores data l Forms – screen objects used to maintain, view, and print from a database l Reports – provides formatted output l Switchboards – a set of special forms used to provide controlled access to the data, forms, report and other objects in a database

36 Figures 1.10 and 1.11: Part and Order Forms

37 Figure 1.12: Parts Report

38 Figure 1.13: Main Switchboard

39 Figure 1.14: Main Data Switchboard

40 Figure 1.15: Advantages of Database Processing

41 Figure 1.16: Disadvantages of Database Processing

42 Introduction to Henry Books Database Case u Book store chain operated by Ray Henry u Henry decided to use database to gather and store information on: l Branches l Publishers l Authors l Books

43 Figure 1.17: Sample Branch Data

44 Figure 1.17: Sample Publisher Data (con’t.)

45 Figure 1.18: Sample Author Data

46 Figure 1.19: Sample Book Data

47 Figure 1.20: Wrote Table Relates Authors to Books

48 Figure 1.20: Inventory Table Relates Branches to Books (con’t.)

49 Summary u Nondatabase approaches to management have problems with replication, redundancy, sharing, limited security, and size limitations u Entity - a person, place, object, event, or idea for which you want to store and process data u Attribute, field, or column - a characteristic or property of an entity u Relationship - an association between entities

50 Summary u One-to-many relationship - exists when l Each occurrence of the first entity is related to many occurrences of the second entity l Each occurrence of the second entity is related to only one occurrence of the first entity u Database is a structure that can store information about multiple types of entities u An entity-relationship (E-R) diagram represents a database pictorially u Database management system (DBMS) - a program, or a collection of programs, through which users interact with a database

51 Summary u Advantages to database processing: l Getting more information from the same amount of data l Sharing data l Balancing conflicting requirements l Controlling redundancy l Facilitating consistency l Improving integrity l Expanding security l Increasing productivity l Providing data independence

52 Summary u Disadvantages of database processing: l Larger file size l Increased complexity l Greater impact of failure l More difficult recovery