All Powder Board and Ski Microsoft Access Workbook Chapter 2: Database Design Jerry Post Copyright © 2003

DBDesign: An Expert System Benefits Makes it easy to create database diagrams Saves data in central location, so changes can be made from almost any computer Provides immediate detailed feedback on the design Requirements Instructors must ask for a free account Instructors and students need a Java-enabled Web browser

Access Data Types (Domains) NameDataBytes Text (characters) fixed variable memo NA Text Memo K Variable Numeric Byte (8 bits) Integer (16 bits) Long (32 bits) (64 bits) Fixed precision Float Double Currency Yes/No Number: Byte Number: Integer Number: Long Integer NA Number: Decimal Number: Single Number: Double Currency Yes/No / /- 2 billion +/- 1 E 28 +/- 1 E 38 +/- 1 E 308 +/ trillion 0/ bit Date/Time 1/1/100 – 12/31/9999 (1 sec)8 ImageOLE Object1 gigabyteVariable AutoNumber Long (+/- 2 billion)4

Initial Business Objects Employee EmployeeID TaxpayerID LastName FirstName Address City State ZIP Customer CustomerID LastName FirstName Phone Address City State ZIP Sale SaleID SaleDate CustomerID EmployeeID Rental RentID RentDate CustomerID ExpectedReturn

Associations or Relationships Employee EmployeeID TaxpayerID LastName FirstName Address City State ZIP Customer CustomerID LastName FirstName Phone Address City State ZIP Sale SaleID SaleDate CustomerID EmployeeID Rental RentID RentDate CustomerID ExpectedReturn 0…* 1…1

Getting Started Enter the key numbers you received Create a username and password. Enter your correct name, address and StudentID

Class Registration Successful account creation Select your university and class Enter the admit code

DBDesign: Example Available columns Menu Class (entity) Corrections Status line

Relationships Drag-and- drop column Select min and max for both sides of the relationship

Design Errors Add SKU to the Sale table Connect the Inventory table to the Sale table Double click the diagnostic message Possible errors are highlighted

More Errors Try setting SKU as a key It still causes problems because SaleDate does not depend on the SKU

Split Many-to-Many Relationship Sale SaleID SaleDate CustomerID EmployeeID Inventory SKU Size QOH Many-to-Many SaleItem SaleID SKU QuantitySold SalePrice 1…1 0…* 1…* 1…1

Ski Shop Inventory Photo: Ski shops carry multiple lengths of each ski or board model. Model information refers to the overall type of board or ski. Inventory information refers to an individual ski or board— defined by its length. Model: Rossignol Axium Item: 196 cmItem: 181 cm

Models and Items

Customer Skill Level CustomerID, LastName, … Style, SkillLevel Business rule: Each customer can have one skill in many styles. Business rule: Each style can apply to more than one customer. Need a table with both attributes as keys. CustomerID, LastName, … Style, SkillLevel But you cannot include LastName, FirstName and so on, because then you would have to re-enter that data for each customer skill.

Customer Style Skills Customer CustomerID LastName FirstName Phone Address City State ZIP CustomerSkill CustomerID Style SkillLevel Style StyleDescription SkillLevel SkillDescription