Chapter 16 HAI! Adventure Database: Case Study in Database Design

Copyright © 2006 Pearson Addison-Wesley. All rights reserved Strategy for Building a Database Perform a needs analysis –How the database will be used, kinds of data input, kinds of information output Approximate and Revise a Physical Design Implement the Physical Design Design the Logical Database Implement the Logical Database Implement the GUIs Evaluate usefulness and (possibly) revise

Copyright © 2006 Pearson Addison-Wesley. All rights reserved The HAI! Adventure Businesses Business will have shops at resort locations around the world Each shop will offer equipment for a single activity Company will run organized lessons and tours Database design is for rentals and activities only

Copyright © 2006 Pearson Addison-Wesley. All rights reserved The HAI! Adventure Businesses First business is Snow Machine Ski Rental Customer proceeds through stages: –Selection. Customer gives receptionist name, address, contact info –Fitting. Specialist gets weight and ability level information to set ski bindings. Equipment ID numbers are recorded; equipment settings are recorded; gear is given to customer –Payment. Customer signs rental agreement and pays

Copyright © 2006 Pearson Addison-Wesley. All rights reserved Perform a Needs Analysis What information is created and what information is needed to transact the business Created: –personal information on customer –technical information on equipment Needed: –Content of rental agreement (association of customer's personal data with equipment's technical data)

Copyright © 2006 Pearson Addison-Wesley. All rights reserved Needs Analysis (cont'd) Specifically, contract must contain customer's name, address, phone If customer returns, this info will be repeated (redundancy) Need a table of customers (Clients) Need a table for adventure specialists (ASTeam) Rentals table records date, equipment, adjustments, any special information Table now has three tables: –Clients has relationship with Rentals –ASTeam has relationship with Rentals

Copyright © 2006 Pearson Addison-Wesley. All rights reserved Approximate/Revise the DB Design Specify the Clients Table –Customer ID –First –Middle –Last –Birthdate –Street –City –State –ZIP –Country –Home_Phone –Mobile_Phone – –Local_Contact

Copyright © 2006 Pearson Addison-Wesley. All rights reserved Approximate/Revise the DB Design (cont'd) Specify the ASTeam Table –Nickname –First –Middle –Last –Birthdate –SS_Number –Mobil_Phone – –Certified –Cert_Expire –Cert_Detail

Copyright © 2006 Pearson Addison-Wesley. All rights reserved Approximate/Revise the DB Design (cont'd) Employee contact schema –Same schema can be used to set up AS_Home (for permanent employee addresses) and AS_Local (for local employee addresses)

Copyright © 2006 Pearson Addison-Wesley. All rights reserved Approximate/Revise the DB Design (cont'd) Specify the Rentals Table –Customer table key –Specialists table key –The rest of the necessary information about the rental event –Dependencies: Field for Ski? (Y/N) determines if the transaction is for skis and bindings If it is Y, then Weight, Ability, and Settings fields must be filled in These constraints will be enforced in the implementation

Copyright © 2006 Pearson Addison-Wesley. All rights reserved Approximate/Revise the DB Design (cont'd) Specify the Relationships –One-to-Many Relationships Rents, Clients:Rentals relationship Serves, ASTeam:Rentals relationship Home_Of: AS_Home:ASTeam relationship Sleeps_At: AS_Local:ASTeam relationship

Copyright © 2006 Pearson Addison-Wesley. All rights reserved Revise the Physical Design? Assess the table organization and see how well it fulfills the needs of Snow Machine The database has little redundancy, but how well will it work when the business expands to other sports? Details of equipment rented could be moved to a separate table

Copyright © 2006 Pearson Addison-Wesley. All rights reserved Revise the Physical Design? (cont'd) Ensure Unique Fields –Add shop ID number field Introduce New Relationship –By creating new table (Gear) for specific equipment rented, we created a many-to-one relationship between the two

Copyright © 2006 Pearson Addison-Wesley. All rights reserved Implement the Physical DB Design Define the Tables Define the Relationships

Copyright © 2006 Pearson Addison-Wesley. All rights reserved

Copyright © 2006 Pearson Addison-Wesley. All rights reserved

Copyright © 2006 Pearson Addison-Wesley. All rights reserved

Copyright © 2006 Pearson Addison-Wesley. All rights reserved Design the Logical Database To give users views of the database: –Analyze the business activity to identify the information inputs and outputs –Determine what information the specialists need from each view, and where it is stored in the tables –Define a conceptual query for a new table as a join-then-trim process from existing tables –Implement the conceptual query in SQL –Define a GUI to display the information for the specialists

Copyright © 2006 Pearson Addison-Wesley. All rights reserved Design the Logical Database (cont'd) Three customer-related views: –Sign-in: Receptionist establishes new rental and enters data about customer into Clients table –Fitting: In fitting room, specialist enters own name into Rentals table and equipment into Gears table –Agreement:Customer takes gear back to receptionist to sign and pay. Price is entered. Information in Clients, Gear, ASTeam, Rentals tables must be combined into contract and printed Employee-related view: –Hiring. New hiring, employee's information entered into three tables: ASTeam, AS_Home, AS_Local

Copyright © 2006 Pearson Addison-Wesley. All rights reserved Analyze the Tables for the Views Logical Tables computed by queries –Sign-in: Requires Rental_ID and Customer fields from Rentals table; ASTeamer field; all fields of Clients table; Ski? field from Gear table –Fitting: All fields from Gear; Rental_ID and ASTeamer fields from Rentals table; First and Last fields from Clients table –Agreement: All fields from Rentals table; all fields from Clients (except and Local_Contact); and Gear and specialist's name field from ASTeam field –Hiring: All fields from ASTeam, AS_Home and AS_Local

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Copyright © 2006 Pearson Addison-Wesley. All rights reserved Create the View Queries Views will be created using queries –Combine the base tables into a super table and then retrieve the items needed for the view Sign-in Query: –Begins a rental (establishes a new Rentals row) –Needs Rental_ID and Customer.ASTeamer from Rentals table; all the fields from Clients table, and Ski? field from Gear table

Copyright © 2006 Pearson Addison-Wesley. All rights reserved Create the View Queries Fitting Query: –Needs Rental_ID, ASTeamer, and Customer fields from Rentals table; all fields from Gear table Agreement Query: –All fields from first three tables except Clients. and Clients.Local_Contract; and name field from ASTeam Hiring Query: –All the fields from the three tables: ASTeam, AS_Home, AS_Local

Copyright © 2006 Pearson Addison-Wesley. All rights reserved Implement the Logical Database Design Encode the Hiring Query –Simply the join of three tables Conceptual natural join produces table with all fields, but SQL is necessary to specify which fields should be included (SELECT…FROM) Operator is INNER JOIN Give equality test that is the basis for the INNER JOIN All references to fields use the table name.field name syntax

Copyright © 2006 Pearson Addison-Wesley. All rights reserved Implement the Logical Database Design (cont'd) Encode the Sign-in Query and the Fitting Query –Follow the same guidelines Encode the Agreement Query –Uses all fields (but two) of three tables, and only three fields of the other, so the SQL is not conceptually difficult

Copyright © 2006 Pearson Addison-Wesley. All rights reserved Implementing The GUIs To make data entry friendlier Guidelines –Arrange information sensibly Cluster related fields, orient in expected ways –Avoid Clutter Eliminate duplicate fields, avoid unnecessary text, lines, and visual effect –Preload fields Fill a field with a default value or expected format (like DD/MM/YYYY)

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Copyright © 2006 Pearson Addison-Wesley. All rights reserved

Copyright © 2006 Pearson Addison-Wesley. All rights reserved Extending a DB: Lessons and Tours Consider what changes are needed to move into the lessons and tours business An Analogy: –Think about organizing table as a class list –Each group has a leader and a set of participants –Problems: Data that should be independent is bound— student list should not be ordered

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Copyright © 2006 Pearson Addison-Wesley. All rights reserved The Activities Table Improved design: Create an entity that includes the common features and properties of the lessons and tours (scheduled activity) Fields: –Activity_ID –Date –Leader –Description –Limit (on number of participants) All activities look alike in the database because the nature of the activity is specified in the description field

Copyright © 2006 Pearson Addison-Wesley. All rights reserved The Apply Table How will we create a participants table? Use the concept of registration to bind Clients and Activities Like Rentals, but without the equipment table Fields: –Shop_ID; Regist_ID; Date; Activity; Participant; Skill; Payment If a person registered for more than one activity, he or she has more than one row in Apply table, independent

Copyright © 2006 Pearson Addison-Wesley. All rights reserved Establish Relationships between Tables Creating the Activities and Apply tables for the physical database naturally defines some relationships –Leads, the ASTeam:Activities relationship –Offers, the Activities:Apply relationship –Registers_For, the Clients:Apply relationship All one-to-many relationships

Copyright © 2006 Pearson Addison-Wesley. All rights reserved Establish Relationships between Tables (cont'd) Create the participants list: –Join Activities, Apply, and Customers tables, and extract necessary fields All fields from Activities; participants' names from Clients. Apply is only used for associating Activities table entries to Clients table entries

Copyright © 2006 Pearson Addison-Wesley. All rights reserved A Class List Report Attends_Q query will create a table of all the students who signed up for all the classes To create a list for one class, or one day –Use Activity_ID or Date to select necessary rows from Attends_Q table –Just add a WHERE clause to Attends_Q query that saves only those rows that meet the criterion

Copyright © 2006 Pearson Addison-Wesley. All rights reserved

Copyright © 2006 Pearson Addison-Wesley. All rights reserved

Copyright © 2006 Pearson Addison-Wesley. All rights reserved

Copyright © 2006 Pearson Addison-Wesley. All rights reserved