1. Database Design University of California, Berkeley
School of Information Management and Systems
SIMS 202: Information Organization and Retrieval
11/30/2000
Information Organization and Retrieval

2. Information Organization and Retrieval
Last Time
Databases and Files
Database design
Database life cycle
Data Models
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Information Organization and Retrieval

3. Information Organization and Retrieval
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
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Information Organization and Retrieval

4. Information Organization and Retrieval
Database Environment
CASE
Tools
DBMS
User
Interface
Application
Programs
Repository
Database
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Information Organization and Retrieval

5. Information Organization and Retrieval
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
Database
Application
Programs
Database contains:
User’s Data
Metadata
Indexes
Application Metadata
User
Interface
Applications
Kroenke, Database
Processing
11/30/2000
Information Organization and Retrieval

6. Information Organization and Retrieval
Terms and Concepts
Database:
A collection of similar records with relationships between the records. (Rowley)
A Database is a collection of stored operational data used by the application systems of some particular enterprise. (C.J. Date)
11/30/2000
Information Organization and Retrieval

7. Information Organization and Retrieval
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
11/30/2000
Information Organization and Retrieval

8. Information Organization and Retrieval
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
11/30/2000
Information Organization and Retrieval

9. Information Organization and Retrieval
Terms and Concepts
Models
(1) Levels or views of the Database
Conceptual, logical, physical
(2) DBMS types
Relational, Hierarchic, Network, Object-Oriented, Object-Relational
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Information Organization and Retrieval

10. Information Organization and Retrieval
Models (1)
Conceptual
Model
Logical
External
requirements
Application 1
Application 2
Application 3
Application 4
Internal Model
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Information Organization and Retrieval

11. Database System Life Cycle
Physical
Creation 2
Conversion 3
Design 1
Growth,
Change, &
Maintenance 6
Integration 4
Operations 5
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Information Organization and Retrieval

12. Another View of the Life Cycle
Integration 4
Operations 5
Design 1
Physical
Creation 2
Conversion 3
Growth,
Change 6
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Information Organization and Retrieval

13. Information Organization and Retrieval
Database Models
Models(2): DBMS types
Hierarchical
Network
Relational
Object-Oriented
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Information Organization and Retrieval

14. Information Organization and Retrieval
Database Data Models
Hierarchical Model
Similar to data structures in programming languages.
Books
(id, title)
Publisher
Subjects
Authors
(first, last)
11/30/2000
Information Organization and Retrieval

15. Information Organization and Retrieval
Database Data Models
Network Model
Provides for single entries of data and navigational “links” through chains of data.
Subjects
Books
Authors
Publishers
11/30/2000
Information Organization and Retrieval

16. Information Organization and Retrieval
Database Data Models
Relational Model
Provides a conceptually simple model for data as relations (typically considered “tables”) with all data visible.
11/30/2000
Information Organization and Retrieval

17. Information Organization and Retrieval
Database Data Models
Object Oriented Data Model
Encapsulates data and operations as “Objects”
Books
(id, title)
Publisher
Subjects
Authors
(first, last)
11/30/2000
Information Organization and Retrieval

18. Information Organization and Retrieval
Today
More on Database Design Process
Conceptual Model and ER Diagrams
Creating the Logical Model
Mapping ER diagrams to Relational tables
11/30/2000
Information Organization and Retrieval

19. Database Design Process
Application 1
Application 2
Application 3
Application 4
External
Model
External
Model
External
Model
External
Model
Application 1
Conceptual
requirements
Application 2
Conceptual
requirements
Conceptual
Model
Logical
Model
Internal Model
Application 3
Conceptual
requirements
Application 4
Conceptual
requirements
11/30/2000
Information Organization and Retrieval

20. Database Design Process
Conceptual Requirements
Systems Analysis Process
Examine all of the information sources used in existing applications
Identify the characteristics of each data element
numeric
text
date/time
etc.
Examine the tasks carried out using the information
Examine results or reports created using the information
11/30/2000
Information Organization and Retrieval

21. Database Design Process
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?
11/30/2000
Information Organization and Retrieval

22. Database Design Process
Logical Model
How is each entity and relationship represented in the Data Model of the DBMS
Hierarchic?
Network?
Relational?
Object-Oriented?
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Information Organization and Retrieval

23. Database Design Process
Internal Model
Choices of index file structure
Choices of data storage formats
Choices of disk layout
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Information Organization and Retrieval

24. Database Design Process
External Model
User views of the integrated database
Making the old (or updated) applications work with the new database design
11/30/2000
Information Organization and Retrieval

25. 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.
11/30/2000
Information Organization and Retrieval

26. Information Organization and Retrieval
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
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Information Organization and Retrieval

27. Information Organization and Retrieval
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
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Information Organization and Retrieval

28. Information Organization and Retrieval
Relationships
Relationships are the associations between entities. They can involve one or more entities and belong to particular relationship types
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Information Organization and Retrieval

29. Information Organization and Retrieval
Relationships
Class
Attends
Student
Part
Supplies
project
parts
Supplier
Project
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Information Organization and Retrieval

30. Types of Relationships
Concerned only with cardinality of relationship
Truck
Assigned
Employee
Project 1 n m
Chen ER notation
11/30/2000
Information Organization and Retrieval

31. Information Organization and Retrieval
Other Notations
Truck
Assigned
Employee
Project
Assigned
Employee
Project
Assigned
Employee
“Crow’s Foot”
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Information Organization and Retrieval

32. Information Organization and Retrieval
Other Notations
Truck
Assigned
Employee
Project
Assigned
Employee
Project
Assigned
Employee
IDEFIX Notation
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Information Organization and Retrieval

33. More Complex Relationships
Project
Evaluation
Employee
Manager
1/n/n
1/1/1
n/n/1
SSN
Date
Project
Project
Assigned
Employee
4(2-10) 1
Manages 1
Manages
Employee
Is Managed By n
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Information Organization and Retrieval

34. Information Organization and Retrieval
Weak Entities
Owe existence entirely to another entity
Order-line
Contains
Order
Invoice #
Part#
Rep#
Quantity
Invoice#
11/30/2000
Information Organization and Retrieval

35. Supertype and Subtype Entities
Clerk
Is one of
Sales-rep
Invoice
Other
Employee
Sold
Manages
11/30/2000
Information Organization and Retrieval

36. Many to Many Relationships
Project Is
Assigned
Assignment
SSN
Proj#
Hours
Employee
11/30/2000
Information Organization and Retrieval

37. Developing a Conceptual Model
We will look at a small business
Assume that we have done interviews with the business and found out the following information about the forms used and types of information kept in files and used for business operations...
11/30/2000
Information Organization and Retrieval

38. Primary Business Operations
The business (ACME Widget Co.) sells parts to customers.
Each part has:
A part number,
A selling price,
A description of the part,
The count of the part currently in stock.
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Information Organization and Retrieval

39. Business Operations (cont.)
Each sale is on an invoice to one customer.
Invoices contain:
Line items for each part ordered,
Total amount due for the invoice,
Customer information:
Company name, address, and an ID number.
Invoices are written up by one sales representative, who is credited with the sale
Sales reps are paid a 5% commission on sales.
11/30/2000
Information Organization and Retrieval

40. Business Operations (cont.)
Information must be kept on inventory of parts.
There are multiple suppliers of parts:
The prices charged by different suppliers for a given part may be different. This is the Cost of the part.
11/30/2000
Information Organization and Retrieval

41. Business Operations (cont.)
Employee information includes:
Name,
Social Security Number,
Employee ID number,
Address,
Position.
Hourly wages must be tracked for all employees (except sales reps).
11/30/2000
Information Organization and Retrieval

42. Business Operations (cont.)
One account is kept for each customer to track charges, payments, and the current balance.
The company needs to know if an order has been shipped.
The accounting department must know which invoices have been paid.
The total sales for each sales rep must be calculated.
11/30/2000
Information Organization and Retrieval

43. Business Operations (cont.)
We must know if a part is in stock at the company or on order from a supplier.
Each hourly employee generates a time-card every Monday morning.
Sales Reps don’t turn in time-cards, just their total sales.
All employees are paid weekly by check.
We need a report each Monday telling us what each employee should be paid for the previous week.
11/30/2000
Information Organization and Retrieval

44. Information Organization and Retrieval
Entities
Customer
Invoice
Employee
Inventory
Supplier
Account
Sales Rep
Parts
Timecard
Check
11/30/2000
Information Organization and Retrieval

45. Information Organization and Retrieval
Functional areas
Ordering
Inventory
Supplies
Shipping
Personnel
Payroll
We will concentrate on Ordering and Inventory
11/30/2000
Information Organization and Retrieval

46. Information Organization and Retrieval
Ordering
Invoice
Rep-cust
invoice
Sales-Rep
Customer
Simple Ternary
Relationship
11/30/2000
Information Organization and Retrieval

47. Information Organization and Retrieval
Ordering
Invoice
Orders
Customer
Cust#
Writes
Sales-Rep
Invoice#
Rep#
Parts
Repeating
attribute
11/30/2000
Information Organization and Retrieval

48. Ordering Normalization
Orders
Customer
Cust#
Invoice
Writes
Sales-Rep
Invoice#
Rep#
Line-Item
Contains
Part#
Quantity
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Information Organization and Retrieval

49. Information Organization and Retrieval
Parts and Suppliers
Part
Supplies
Supplier
Company#
Includes
Line-Item
Part#
Count
Price
Invoice# m n
Is this correct?
Where does Price
belong?
11/30/2000
Information Organization and Retrieval

50. Parts and Suppliers (alternative 2)
Company#
Contains
Line-Item
Part#
Invoice#
Part
Count
Price n m
Supplier
Offers
Supplied-Part
Cost
Supplies
Intersection
Entity
11/30/2000
Information Organization and Retrieval

51. Parts and Suppliers (Alternative 3)
Company#
Contains
Line-Item
Part#
Invoice#
Part
Count
Price
Supplier
Supplies
Supplied-Part
Cost
11/30/2000
Information Organization and Retrieval

52. Parts and Suppliers (Alternative Notation 4)
Company#
Contains
Line-Item
Part#
Invoice#
Part
Count
Price m
Supplier
Cost
Supplying
11/30/2000
Information Organization and Retrieval

53. Parts and Suppliers (Alternative Notation 5)
Cost
Supplier
Company#
Supplies
Part
Part#
Count
Price m
11/30/2000
Information Organization and Retrieval

54. Information Organization and Retrieval
Orders
Customer
Cust#
Invoice
Writes
Sales-Rep
Invoice#
Sales
Rep#
Line-Item
Contains
Part#
Quantity
Part
Count
Price
Supplier
Company#
Ordered
Hourly
Employee
ISA
Emp#
Wage
Cost
Supplied
Has
On-Order
Supplies
ER Model
11/30/2000
Information Organization and Retrieval

55. Mapping to a Relational Model
Each entity in the ER Diagram becomes a relation.
A properly normalized ER diagram will indicate where intersection relations for many-to-many mappings are needed.
Relationships are indicated by common columns (or domains) in tables that are related.
We will examine the tables for the Acme Widget Company derived from the ER diagram
11/30/2000
Information Organization and Retrieval

56. Information Organization and Retrieval
Employee
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Information Organization and Retrieval

57. Information Organization and Retrieval
Sales-Rep
Hourly
11/30/2000
Information Organization and Retrieval

58. Information Organization and Retrieval
Customer
11/30/2000
Information Organization and Retrieval

59. Information Organization and Retrieval
Invoice
11/30/2000
Information Organization and Retrieval

60. Information Organization and Retrieval
Line-Item
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Information Organization and Retrieval

61. Information Organization and Retrieval
Part
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Information Organization and Retrieval

62. Information Organization and Retrieval
Joins
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Information Organization and Retrieval

63. Information Organization and Retrieval
Next Time
More on normalization
SQL
Effectiveness and Efficiency criteria for database designs
Advantages and failings of DBMS technology
11/30/2000
Information Organization and Retrieval