1. 2005-10-06 - SLIDE 1IS 202 – FALL 2005 Prof. Ray Larson UC Berkeley SIMS SIMS 202: Information Organization and Retrieval Introduction to Database Design

2. 2005-10-06 - SLIDE 2IS 202 – FALL 2005 Lecture Overview Databases and Database Design Database Life Cycle Database Design ER Diagrams Discussion

3. 2005-10-06 - SLIDE 3IS 202 – FALL 2005 Lecture Overview Databases and Database Design Database Life Cycle Database Design ER Diagrams Discussion

4. 2005-10-06 - SLIDE 4IS 202 – FALL 2005 What is a Database?

5. 2005-10-06 - SLIDE 5IS 202 – FALL 2005 Files and Databases File: A collection of records or documents dealing with one organization, person, area or subject (Rowley) –Manual (paper) files –Computer files Database: A collection of similar records with relationships between the records (Rowley) –Bibliographic, statistical, business data, images, etc.

6. 2005-10-06 - SLIDE 6IS 202 – FALL 2005 Database A Database is a collection of stored operational data used by the application systems of some particular enterprise (C.J. Date) –Paper “Databases” Still contain a large portion of the world’s knowledge –File-Based Data Processing Systems Early batch processing of (primarily) business data –Database Management Systems (DBMS)

7. 2005-10-06 - SLIDE 7IS 202 – FALL 2005 Why DBMS? History –50’s and 60’s all applications were custom built for particular needs –File based –Many similar/duplicative applications dealing with collections of business data –Early DBMS were extensions of programming languages –1970 - E.F. Codd and the Relational Model –1979 - Ashton-Tate and first Microcomputer DBMS

8. 2005-10-06 - SLIDE 8IS 202 – FALL 2005 From File Systems to DBMS Problems with file processing systems –Inconsistent data –Inflexibility –Limited data sharing –Poor enforcement of standards –Excessive program maintenance

9. 2005-10-06 - SLIDE 9IS 202 – FALL 2005 DBMS Benefits Minimal data redundancy Consistency of data Integration of data Sharing of data Ease of application development Uniform security, privacy, and integrity controls Data accessibility and responsiveness Data independence Reduced program maintenance

10. 2005-10-06 - SLIDE 10IS 202 – FALL 2005 Terms and Concepts Data independence –Physical representation and location of data and the use of that data are separated The application doesn’t need to know how or where the database has stored the data, but just how to ask for it Moving a database from one DBMS to another should not have a material effect on application program Recoding, adding fields, etc. in the database should not affect applications

11. 2005-10-06 - SLIDE 11IS 202 – FALL 2005 Database Environment CASE Tools DBMS User Interface Application Programs Repository Database

12. 2005-10-06 - SLIDE 12IS 202 – FALL 2005 Database Components DBMS =============== Design tools Table Creation Form Creation Query Creation Report Creation Procedural language compiler (4GL) ============= Run time Form processor Query processor Report Writer Language Run time User Interface Applications Application Programs Database Database contains: User’s Data Metadata Indexes Application Metadata

13. 2005-10-06 - SLIDE 13IS 202 – FALL 2005 Types of Database Systems PC databases Centralized database Client/server databases Distributed databases Database models

14. 2005-10-06 - SLIDE 14IS 202 – FALL 2005 PC Databases E.g.: Access FoxPro Dbase Etc.

15. 2005-10-06 - SLIDE 15IS 202 – FALL 2005 Centralized Databases Central Computer

16. 2005-10-06 - SLIDE 16IS 202 – FALL 2005 Client Server Databases Network Client Database Server

17. 2005-10-06 - SLIDE 17IS 202 – FALL 2005 Distributed Databases computer Location A Location C Location B Homogeneous Databases

18. 2005-10-06 - SLIDE 18IS 202 – FALL 2005 Distributed Databases Local Network Database Server Client Comm Server Remote Comp. Remote Comp. Heterogeneous Or Federated Databases

19. 2005-10-06 - SLIDE 19IS 202 – FALL 2005 Terms and Concepts A “database application” is an application program (or set of related programs) that is used to perform a series of database activities: –Create Add new data to the database –Read Read current data from the database –Update Update or modify current database data –Delete Remove current On behalf of database users

20. 2005-10-06 - SLIDE 20IS 202 – FALL 2005 Terms and Concepts Enterprise –Organization Entity –Person, Place, Thing, Event, Concept... Attributes –Data elements (facts) about some entity –Also sometimes called fields or items or domains Data values –Instances of a particular attribute for a particular entity

21. 2005-10-06 - SLIDE 21IS 202 – FALL 2005 Terms and Concepts Key –An attribute or set of attributes used to identify or locate records in a file Primary Key –An attribute or set of attributes that uniquely identifies each record in a file

22. 2005-10-06 - SLIDE 22IS 202 – FALL 2005 Terms and Concepts Models –(1) Levels or views of the Database Conceptual, logical, physical –(2) DBMS types Relational, Hierarchic, Network, Object-Oriented, Object-Relational

23. 2005-10-06 - SLIDE 23IS 202 – FALL 2005 Models (1) Conceptual Model Logical Model External Model Conceptual requirements Conceptual requirements Conceptual requirements Conceptual requirements Application 1 Application 2Application 3Application 4 Application 2 Application 3 Application 4 External Model External Model External Model Internal Model More later on this…

24. 2005-10-06 - SLIDE 24IS 202 – FALL 2005 Data Models(2): History Hierarchical Model (1960’s and 1970’s) –Similar to data structures in programming languages Books (id, title) PublisherSubjects Authors (first, last)

25. 2005-10-06 - SLIDE 25IS 202 – FALL 2005 Data Models(2): History Network Model (1970’s) –Provides for single entries of data and navigational “links” through chains of data. SubjectsBooks Authors Publishers

26. 2005-10-06 - SLIDE 26IS 202 – FALL 2005 Data Models(2): History Relational Model (1980’s) –Provides a conceptually simple model for data as relations (typically considered “tables”) with all data visible

27. 2005-10-06 - SLIDE 27IS 202 – FALL 2005 Data Models(2): History Object Oriented Data Model (1990’s) –Encapsulates data and operations as “Objects” Books (id, title) PublisherSubjects Authors (first, last)

28. 2005-10-06 - SLIDE 28IS 202 – FALL 2005 Data Models(2): History Object-Relational Model (1990’s) –Combines the well-known properties of the Relational Model with such OO features as: User-defined datatypes User-defined functions Inheritance and sub-classing All of the major enterprise DBMS systems are now Object-Relational or incorporate Object-Relational features

29. 2005-10-06 - SLIDE 29IS 202 – FALL 2005 Lecture Overview Databases and Database Design Database Life Cycle Database Design ER Diagrams Discussion

30. 2005-10-06 - SLIDE 30IS 202 – FALL 2005 Database System Life Cycle Growth, Change, & Maintenance 6 Operations 5 Integration 4 Design 1 Conversion 3 Physical Creation 2

31. 2005-10-06 - SLIDE 31IS 202 – FALL 2005 Design (more later) Determination of the needs of the organization –That is: “what are the business rules of this organization”, what information does it use and need? Development of the Conceptual Model of the database –In Database design this is typically done with Entity- Relationship diagramming techniques Construction of a Data Dictionary Development of the Logical Model

32. 2005-10-06 - SLIDE 32IS 202 – FALL 2005 Physical Creation Development of the Physical Model of the Database –Data formats and types –Determination of indexes, etc. Load a prototype database and test Determine and implement security, privacy and access controls Determine and implement integrity constraints

33. 2005-10-06 - SLIDE 33IS 202 – FALL 2005 Conversion Convert existing data sets and applications to use the new database –May need programs, conversion utilities to convert old data to new formats

34. 2005-10-06 - SLIDE 34IS 202 – FALL 2005 Integration Overlaps with Phase 3 Integration of converted applications and new applications into the new database

35. 2005-10-06 - SLIDE 35IS 202 – FALL 2005 Operations All applications run full-scale Privacy, security, access control must be in place Recovery and Backup procedures must be established and used

36. 2005-10-06 - SLIDE 36IS 202 – FALL 2005 Growth, Change, and Maintenance Change is a way of life –Applications, data requirements, reports, etc. will all change as new needs and requirements are found –The Database and applications and will need to be modified to meet the needs of changes

37. 2005-10-06 - SLIDE 37IS 202 – FALL 2005 Another View of the Life Cycle Operations 5 Conversion 3 Physical Creation 2 Growth, Change 6 Integration 4 Design 1

38. 2005-10-06 - SLIDE 38IS 202 – FALL 2005 Lecture Overview Databases and Database Design Database Life Cycle Database Design ER Diagrams Discussion

39. 2005-10-06 - SLIDE 39IS 202 – FALL 2005 Database design process Conceptual Model Logical Model External Model Conceptual requirements Conceptual requirements Conceptual requirements Conceptual requirements Application 1 Application 2Application 3Application 4 Application 2 Application 3 Application 4 External Model External Model External Model Internal Model

40. 2005-10-06 - SLIDE 40IS 202 – FALL 2005 Conceptual Design Conceptual Model –Merge the collective needs of all applications –Determine what Entities are being used Some object about which information is to maintained –What are the Attributes of those entities? Properties or characteristics of the entity What attributes uniquely identify the entity –What are the Relationships between entities How the entities interact with each other?

41. 2005-10-06 - SLIDE 41IS 202 – FALL 2005 Developing a Conceptual Model Overall view of the database that integrates all the needed information discovered during the requirements analysis Elements of the Conceptual Model are represented by diagrams, Entity-Relationship or ER Diagrams, that show the meanings and relationships of those elements independent of any particular database systems or implementation details Can also be represented using other modeling tools (such as UML)

42. 2005-10-06 - SLIDE 42IS 202 – FALL 2005 Database Design Process Conceptual Model Logical Model External Model Conceptual requirements Conceptual requirements Conceptual requirements Conceptual requirements Application 1 Application 2Application 3Application 4 Application 2 Application 3 Application 4 External Model External Model External Model Internal Model

43. 2005-10-06 - SLIDE 43IS 202 – FALL 2005 Logical Design Logical Model –How is each entity and relationship represented in the Data Model of the DBMS Hierarchic? Network? Relational? Object-Oriented?

44. 2005-10-06 - SLIDE 44IS 202 – FALL 2005 Database Design Process Conceptual Model Logical Model External Model Conceptual requirements Conceptual requirements Conceptual requirements Conceptual requirements Application 1 Application 2Application 3Application 4 Application 2 Application 3 Application 4 External Model External Model External Model Internal Model

45. 2005-10-06 - SLIDE 45IS 202 – FALL 2005 Physical Design Internal Model –Choices of index file structure –Choices of data storage formats –Choices of disk layout

46. 2005-10-06 - SLIDE 46IS 202 – FALL 2005 Database Design Process Conceptual Model Logical Model External Model Conceptual requirements Conceptual requirements Conceptual requirements Conceptual requirements Application 1 Application 2Application 3Application 4 Application 2 Application 3 Application 4 External Model External Model External Model Internal Model

47. 2005-10-06 - SLIDE 47IS 202 – FALL 2005 Database Application Design External Model –User views of the integrated database –Making the old (or updated) applications work with the new database design

48. 2005-10-06 - SLIDE 48IS 202 – FALL 2005 Lecture Overview Databases and Database Design Database Life Cycle Database Design ER Diagrams Discussion

49. 2005-10-06 - SLIDE 49IS 202 – FALL 2005 ER Diagrams You have already seen a UML form of one…

50. 2005-10-06 - SLIDE 50IS 202 – FALL 2005 ER Diagrams Entity-Relationship (ER) diagrams are concerned with the entities involved in the organization/database and the relationships between those entities (as well as the attributes of each entity

51. 2005-10-06 - SLIDE 51IS 202 – FALL 2005 Entity An Entity is an object in the real world (or even imaginary worlds) about which we want or need to maintain information –Persons (e.g.: customers in a business, employees, authors) –Things (e.g.: purchase orders, meetings, parts, companies) Employee

52. 2005-10-06 - SLIDE 52IS 202 – FALL 2005 Attributes Attributes are the significant properties or characteristics of an entity that help identify it and provide the information needed to interact with it or use it (this is the Metadata for the entities) Employee Last Middle First Name SSN Age Birthdate Projects

53. 2005-10-06 - SLIDE 53IS 202 – FALL 2005 Relationships Relationships are the associations between entities They can involve one or more entities and belong to particular relationship types

54. 2005-10-06 - SLIDE 54IS 202 – FALL 2005 Relationships Class Attends Student Part Supplies project parts Supplier Project

55. 2005-10-06 - SLIDE 55IS 202 – FALL 2005 Types of Relationships Concerned only with cardinality of relationship Truck Assigned EmployeeProject Assigned EmployeeProject Assigned Employee 11 n n 1 m Chen ER notation

56. 2005-10-06 - SLIDE 56IS 202 – FALL 2005 Other Notations Truck Assigned EmployeeProject Assigned EmployeeProject Assigned Employee “Crow’s Foot”

57. 2005-10-06 - SLIDE 57IS 202 – FALL 2005 Other Notations Truck Assigned EmployeeProject Assigned EmployeeProject Assigned Employee IDEFIX Notation

58. 2005-10-06 - SLIDE 58IS 202 – FALL 2005 More Complex Relationships Project Evaluation Employee Manager 1/n/n 1/1/1 n/n/1 Project Assigned Employee 4(2-10) 1 SSNProjectDate Manages Employee Manages Is Managed By 1 n

59. 2005-10-06 - SLIDE 59IS 202 – FALL 2005 Weak Entities Owe existence entirely to another entity Order-line Contains Order Invoice # Part# Rep# QuantityInvoice#

60. 2005-10-06 - SLIDE 60IS 202 – FALL 2005 Supertype and Subtype Entities Clerk Is one of Sales-rep Invoice Other Employee Sold Manages

61. 2005-10-06 - SLIDE 61IS 202 – FALL 2005 Many to Many Relationships Employee Project Is Assigned Project Assignment Assigned SSN Proj# SSN Proj# Hours

62. 2005-10-06 - SLIDE 62IS 202 – FALL 2005 UML diagraming ER diagrams are often now expressed using UML instead…

63. 2005-10-06 - SLIDE 63IS 202 – FALL 2005 UML Class Diagram DIVEORDS Order No Customer No Sale Date Shipvia PaymentMethod CCNumber No of People Depart Date Return Date Destination Vacation Cost CalcTotalInvoice() CalcEquipment() Class Name List of Attributes List of operations

64. 2005-10-06 - SLIDE 64IS 202 – FALL 2005 Differences from Entities in ER Entities can be represented by Class diagrams But Classes of objects also have additional operations associated with them

65. 2005-10-06 - SLIDE 65IS 202 – FALL 2005 Operations Three basic types for database –Constructor –Query –Update

66. 2005-10-06 - SLIDE 66IS 202 – FALL 2005 Associations An association is a relationship that describes a set of links between or among objects. An association can have a name that describes the nature of this relationship. You can put a triangle next to this name to indicate the direction in which the name should be read.

67. 2005-10-06 - SLIDE 67IS 202 – FALL 2005 Associations An association contains an ordered list of association ends. –An association with exactly two association ends is called a binary association –An association with more than two ends is called an n-ary association.

68. 2005-10-06 - SLIDE 68IS 202 – FALL 2005 Associations: Unary relationships Person Is-married-to 0..1 Employee manages * 0..1 manager

69. 2005-10-06 - SLIDE 69IS 202 – FALL 2005 Associations: Binary Relationship Employee Parking Place One-to-one Is-assigned0..1 Product Line Product One-to-many contains1 * StudentCourse Many-to-many Registers-for* *

70. 2005-10-06 - SLIDE 70IS 202 – FALL 2005 Associations: Ternary Relationships VendorWarehouse * * Supplies Part *

71. 2005-10-06 - SLIDE 71IS 202 – FALL 2005 Association Classes StudentCourse Registers-for * * Registration ________________ Term Grade ________________ CheckEligibility() Computer Account _________________ acctID Password ServerSpace *0..1 issues

72. 2005-10-06 - SLIDE 72IS 202 – FALL 2005 Derived Attributes, Associations, and Roles Student _________ name ssn dateOfBirth /age Course Offering ____________ term section time location Registers-for * 1 Course ____________ crseCode crseTitle creditHrs * * Scheduled-for {age = currentDate – dateOfBirth} * * /Takes /participant Derived attribute Derived role Derived association

73. 2005-10-06 - SLIDE 73IS 202 – FALL 2005 Generalization Employee ____________ empName empNumber address dateHired ____________ printLabel() Hourly Employee _______________ HourlyRate _______________ computeWages() Salaried Employee _______________ Annual Sal stockoption _______________ Contributepension() Consultant _______________ contractNumber billingRate _______________ computeFees()

74. 2005-10-06 - SLIDE 74IS 202 – FALL 2005 Lecture Overview Databases and Database Design Database Life Cycle ER Diagrams Discussion

75. 2005-10-06 - SLIDE 75IS 202 – FALL 2005 Discussion Why use DBMS for web-based system development? Why Not use IR systems? Can you use both? Other Questions?

76. 2005-10-06 - SLIDE 76IS 202 – FALL 2005 Next Time Normalization and the Relational Model