1. Dimu' Rumpak © 2009 by Prentice Hall 1 Getting Started Didimus Rumpak, M.Si. Database Concepts Chapter 1 1

2. Dimu' Rumpak© 2009 by Prentice Hall2 Chapter Objectives Identify the purpose and scope of this book Survey the why, what, and how of database processing Understand the reasons for using a database (why) Learn the functions and components of database systems (what) Know the three major steps in creating a database (how)

3. Dimu' Rumpak© 2009 by Prentice Hall3 Purpose of a Database The purpose of a database is to keep track of things Unlike a spreadsheet, a database may store information that is more complicated than a simple list

4. Dimu' Rumpak© 2009 by Prentice Hall4 Information Complexity: Redundancy In a list, each row is intended to stand on its own. As a result, the same information may be entered several times –For Example: A list of Projects may include the Project Manager’s Name, ID, and Phone Extension. If a particular person is managing 10 projects, his/her information would have to be entered 10 times

5. Dimu' Rumpak© 2009 by Prentice Hall5 Redundancy Issues Redundancy increases input efforts Redundancy increases maintenance efforts Redundancy wastes space and slows down processing Redundancy of information may introduce inconsistencies to the data

6. Dimu' Rumpak© 2009 by Prentice Hall6 Information Complexity: Consistency In a list, each row stands own its own. This makes it difficult to apply consistent business rules Consider a company that provides discounts for certain customers. To find the appropriate discount would require a search of previous customer orders. This takes time and is prone to error

7. Dimu' Rumpak© 2009 by Prentice Hall7 Information Complexity: Partial Data To record information in a list, the record must already exist. This makes it impossible to establish a business rule before a business transaction has occurred For example: An order must be entered before a customer’s discount rate may be saved

8. Dimu' Rumpak© 2009 by Prentice Hall8 Information Complexity: Relationships Among the Data In a list, it is difficult to store information about more than one topic For example: A Project List may have information about the Project, the Project Manager, and the Customer As you can image, this list would require many columns. However, the relationships among the Project, Customer, and Project Manager are important

9. Dimu' Rumpak© 2009 by Prentice Hall9 Addressing the Information Complexities Relational databases are designed to address many of the information complexity issues

10. Dimu' Rumpak© 2009 by Prentice Hall10 Relational Databases A relational database stores information in tables. Each informational topic is stored in its own table In essence, a relational database will break- up a list into several parts. One part for each topic in the list A Project List would be divided into a CUSTOMER Table, a PROJECT Table, and a PROJECT_MANAGER Table

11. Dimu' Rumpak© 2009 by Prentice Hall11 Microsoft Access: A Database Management System (DBMS) To create a relational database, you must use a Database Management System (DBMS) such as Microsoft Access

12. Dimu' Rumpak© 2009 by Prentice Hall12 Putting the Pieces Back Together In our relational database we broke apart our list into several tables. Somehow the tables must be joined back together In a relational database, tables are joined together using the value of the data If a PROJECT has a CUSTOMER, the Customer_ID is stored as a column in the PROJECT table. The value stored in this column can be used to retrieve specific customer information from the CUSTOMER table

13. Dimu' Rumpak© 2009 by Prentice Hall13 Sounds like More Work, Not Less A relational database is more complicated than a list However, a relational database minimizes data redundancy, preserves complex relationships among topics, and allows for partial data Furthermore, a relational database provides a solid foundation for user forms and reports

14. Dimu' Rumpak© 2009 by Prentice Hall14 The User Forms versus Tables Although data is stored in several tables, the user forms will look like lists This makes it easier for the user to understand. However, in the background the data will be stored in several tables

15. Dimu' Rumpak© 2009 by Prentice Hall15 A Closer Look at a Database System The four basic elements of a database are: –Users –Database Applications –Database Management System (DBMS) –Database

16. Dimu' Rumpak© 2009 by Prentice Hall16 Users A user of a database system will provide –Inputs –Modifications –Deletions

17. Dimu' Rumpak© 2009 by Prentice Hall17 Database Applications A database application is a set of one or more computer programs that serves as an intermediary between the user and a DBMS A database application reads, writes, formats, and/or modifies data. Applications produce: –Forms –Queries –Reports

18. Dimu' Rumpak© 2009 by Prentice Hall18 Functions of a Database Application Create and process forms Create and transmit queries Create and process reports Execute application logic Provide control

19. Dimu' Rumpak© 2009 by Prentice Hall19 Structured Query Language (SQL) Structured Query Language (SQL) reads and writes requests for the DBMS Many database applications use SQL to retrieve, format, report, insert, delete, and/or modify data for users

20. Dimu' Rumpak© 2009 by Prentice Hall20 Database Management System (DBMS) A database management system (DBMS) serves as an intermediary between database applications and the database The DBMS manages and controls database activities

21. Dimu' Rumpak© 2009 by Prentice Hall21 Functions of a DBMS Create database Create tables Create supporting structures Read database data Update database data Maintain database structures Enforce rules Control concurrency Provide security Perform backup and recovery

22. Dimu' Rumpak© 2009 by Prentice Hall22 Commercial DBMS Products Microsoft Access Oracle’s Oracle Microsoft’s SQL Server IBM’s DB2 Dbase IV Paradox Foxpro MySQL

23. Dimu' Rumpak© 2009 by Prentice Hall23 Referential Integrity Constraints The DBMS will enforce many constraints. One particularly important constraint is referential integrity Referential integrity ensures that the value of a column in one table is valid based on the values in another table –If a 5 was entered as a CustomerID in the PROJECT table, a Customer having a CustomerID value of 5 must exist in the CUSTOMER table

24. Dimu' Rumpak© 2009 by Prentice Hall24 The Database A database is a self-describing collection of related records Self-describing –The definition of the structure of the database is contained within the database itself –Data describing the structure of data is called metadata As we’ve seen, tables within a relational database are related to each other

25. Dimu' Rumpak© 2009 by Prentice Hall25 Desktop Database Systems Desktop database systems typically: –Have one application –Have only a few tables –Less than ten thousand records –Are simple in design –Involve only one computer –Support one user at a time

26. Dimu' Rumpak© 2009 by Prentice Hall26 Organizational Database Systems Organizational database systems typically: –Support several users simultaneously –Include more than one application –Involve multiple computers –Are complex in design –Have large data sets (more than 10,000 records) –Have many tables –Have many databases

27. Dimu' Rumpak© 2009 by Prentice Hall27 Building a Data Model Requirements Design Implementation

28. Dimu' Rumpak© 2009 by Prentice Hall28 Data Model Requirements and Design Requirements –Determine application(s) requirements –Build data model Design –Tables –Relationships –Indexes –Other structures

29. Dimu' Rumpak© 2009 by Prentice Hall29 Data Model Implementation Implementation –Create database –Create tables and relationships –Create other structures –Populate with data –Build applications and test

30. Dimu' Rumpak© 2009 by Prentice Hall30 Depicting the Data Model: Entity-Relationship (E-R) Diagram PROJECT ProjID ProjDesc StartDate CUSTOMER CustID CustName N:1 0 |

31. Dimu' Rumpak© 2009 by Prentice Hall31 Data Structure Diagram ProjID | ProjDesc | StartDate | CustID CustID | CustName 0<0< |

32. Dimu' Rumpak © 2009 by Prentice Hall 32 Getting Started Didimus Rumpak, M.Si. Database Concepts Chapter 1 1