database design - section 9 - oracle...

Database Design - Section 9 Instructor Guide

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Database Design - Section 9 Page i

Table of Contents

Database Design - Section 9 ............................................................................................................................1 Lesson 1 - Interview with the Director of the Animal Shelter.......................................................................1 What Will I Learn? ........................................................................................................................................4 Why Learn It?................................................................................................................................................5 Tell Me / Show Me........................................................................................................................................6 Try It / Solve It ..............................................................................................................................................8 Lesson 2 - Business Rules of the Animal Shelter ..........................................................................................11 What Will I Learn? ........................................................................................................................................12 Why Learn It?................................................................................................................................................13 Tell Me / Show Me........................................................................................................................................14 Try It / Solve It ..............................................................................................................................................15 Lesson 3 - Creating the Animal Shelter ERD................................................................................................18 What Will I Learn? ........................................................................................................................................19 Why Learn It?................................................................................................................................................20 Tell Me / Show Me........................................................................................................................................21 Try It / Solve It ..............................................................................................................................................26 Lesson 4 - Presentation to the Animal Shelter Client ....................................................................................31 What Will I Learn? ........................................................................................................................................33 Why Learn It?................................................................................................................................................34 Tell Me / Show Me........................................................................................................................................35 Try It / Solve It ..............................................................................................................................................36 Lesson 5 - Final Revisions to the Animal-Shelter ERD ................................................................................38 What Will I Learn? ........................................................................................................................................39 Why Learn It?................................................................................................................................................40 Tell Me / Show Me........................................................................................................................................41 Try It / Solve It ..............................................................................................................................................42


Database Design - Section 9 Page 1

Lesson 1 - Interview with the Director of the Animal Shelter

Lesson 1 - Interview with the Director of the Animal Shelter

Lesson Preparation

The animal shelter is the subject of the next five lessons. In this lesson, students interview the director of the animal shelter (played by you, the instructor) to gather information about the business and its data requirements. In Lesson 2, they formulate business rules and assumptions. In Lesson 3, they create the ERD and prepare for their presentations. In Lesson 4, they present their solutions. In Lesson 5, they make revisions to their solutions based on “client” feedback on their presentations. It is important that you let the students know that they will be presenting on the fourth day. This lesson simulates a client/consultant meeting. You are the director of a city animal shelter (the client) who needs a database. Each group of students is a consulting company, and the group members are consultants.



Explain the two roles to the class: consulting company and client. Conduct the interview between the director and the consulting company to determine business needs of the organization (although the class is divided into groups, the interview can take place between the instructor and the entire class). Instructor must review the FAQ, but not share this with the students. They will conduct an interview to discover this information. Animal Shelter FAQ Why do you need this database? We need to track animals in our shelters. We have so many animals and currently it’s all written down in log books that we keep at the front desks of our shelters. We also want to keep track of who has adopted our animals so we can send thank-you notes and solicit them with our fund-raising efforts. How many shelters do you have? We have an East-Side Shelter and a West-Side Shelter. We may add a North-Side Shelter in the next few years. What kinds of animals do you take in? Dogs and cats, mostly. Sometimes we get a bird or a snake, but not very often. What information do you track about these animals? For cats, we like to know if it’s long-haired or short-haired. For dogs, we like to know the breed and the size: small, medium, large. We like to know the approximate age of all animals. We need to know their health and whether they’re vaccinated and spayed or neutered. Instructor must review the FAQ, but not share this with the students. They will conduct an interview to discover this information. Animal Shelter FAQ Why do you need this database? We need to track animals in our shelters. We have so many animals and currently it’s all written down in log books that we keep at the front desks of our shelters. We also want to keep track of who has adopted our animals so we can send thank-you notes and solicit them with our fund-raising efforts. How many shelters do you have? We have an East-Side Shelter and a West-Side Shelter. We may add a North-Side Shelter in the next few years. What kinds of animals do you take in? Dogs and cats, mostly. Sometimes we get a bird or a snake, but not very often. What information do you track about these animals? For cats, we like to know if it’s long-haired or short-haired. For dogs, we like to know the breed and the size: small, medium, large. We like to know the approximate age of all animals. We need to know their health and whether they’re vaccinated and spayed or neutered.



Anything else special that you want to be able to do? We need to be able to get a list of all unadopted cats, and dogs so they can be posted online in the Cat Lovers and Dog Lovers pages of the website. We’ve been doing that by hand. Oh, and we want to send special mailings to customers (maybe letters, maybe email), but only send dog information to people who are allergic to cats and vice versa! Notes These are the basic notes for the Animal Shelter scenario. Conveying this information will lead your students to an ERD that resembles the Possible Solution document. Please embellish this scenario as much as you want in the interview process. Keep in mind that any business requirement you share will change the details and possibly the structure of the ERDs that students create. Depending on how comfortable you are, modify information (you may want to withhold a couple of details so that in a later lesson about refining the ER model, the "director" can say, "I completely forgot. I will need the system to track XY and Z...."). Just be sure to keep track of the information you share so that the student ERDs and Business Requirements documents can be evaluated appropriately.

What to Watch For Most students get excited about the details of the animal shelter. Are there dogs? Are there cats? What about the dogs; what about the cats? You may need to take a time-out to share with the students as an instructor, not as the director, that the #1 thing they need to know before they start is "What do you eventually want the system to do?" This seems obvious, but it's easy to get carried away by the details of an animal shelter and forget to ask the basic question. Remind them that this is the #1 job of a consultant: understanding the needs, so an appropriate system (database first!) can be built and delivered. The #2 question that needs to be answered is “What do you currently do at the animal shelter to handle these needs?” Most students miss this question as well -- you can help them out! Make notes about participation as a component of the evaluation.

Connections Connect the activity to a real-world business. Ask students who have pets to call their veterinarians and ask what kind of database information they record for their clients and their pets. Share the information with the class.



What Will I Learn?

What Will I Learn?



Why Learn It?

Why Learn It?



Tell Me / Show Me

Tell Me / Show Me

Tell Me / Show Me

Instructions: Divide students into groups of 3 or 4 and have them choose a meaningful name for their consulting company. Explain the scenario to the class: As director of the city animal shelter, you have contacted several consulting companies (the student groups) to design a database for the animal shelter. Each consulting company will have an opportunity to conduct an interview to gather information needed to design the database. Ask students to spend about 15 minutes generating a list of questions for the director of the animal shelter. Explain that the interview process can be broken down into the following steps: 1. Preparing for the Interview Before meeting with a client, you must know what you want to accomplish during the interview. Create a list of interview questions based on the information you need by the end of the interview (specific, detailed client expectations/requirements, printed or online copies/formats of current forms, reports, contact persons, schedule of work outline). Assemble the needed materials -- notepad, business card, charts, diagrams, etc.



Make sure you know the names of the clients with whom you will be meeting. Instructions: 2. The Interview Arrive early, but no more than 10 minutes before your appointment. Notify the client if you expect to be delayed. Expect to be nervous at the outset. Nervousness is a natural function that helps you perform your best. Be observant. Be Polite. Address your client by name, asking for correct pronunciation if necessary. Get directly to the point. Discuss only the facts needed. Don't be afraid to ask for clarification. Write notes so you won’t forget! 3. Ending the Interview Summarize the main points with the client to verify that you correctly understand the information provided. Conclude with an expression of continued interest, and be sure you understand the clients decision-making process and time frame before you leave. Reaffirm the primary contact person if additional information is needed. Thank the client for his/her time and consideration. 4. Interview Followup: Transcribe your notes and assess whether you actually got the information you wanted. If not, identify the information that’s missing and determine whether you need to interview the client again. Send a copy of your notes to the client, asking for confirmation of the accuracy and completeness of what you recorded/understood from the interview. The links to real animal-shelter websites will get the students interested. Ask them if they can imagine what the underlying database looks like.



Try It / Solve It

Try It / Solve It

Try It / Solve It

Assessment: Remind students that the data and information requirements of the business will be part of the presentation they will be making in three days. The rubric lists the criteria that will be used to evaluate the activity. Share this with the class. Data and Information requirements The animal shelter would like to track animals in their shelters. They also want to keep track of who has adopted their animals. For all animals, they want to track: name, approximate age, health, whether they’re vaccinated and spayed or neutered, reason being given up, whether good with children, person giving it up.



For cats, they want to know if it’s long-haired or short-haired. For dogs, they want to know the breed and the size: small, medium, large. For animal adopters, they want to track address, phone number, email, dog/cat preference, number of children in their house. For nonadopters who would like to receive the newsletter, they track name, address, email, and phone number. They want to track which cage an animal is in. They want to be able to get a list of all unadopted cats and dogs. They want to send only dog information to people who like dogs and cat information to people who like cats. Assessment:



Assessment: Possible Answer:



Lesson 2 - Business Rules of the Animal Shelter

Lesson 2 - Business Rules of the Animal Shelter

Lesson Preparation

Have students work in their groups to construct the business rules from their interview with the animal-shelter director. Review how to write a business rule. Use an example that applies to the Animal Shelter scenario, such as: Each animal must have a unique identification number. Explain the format in which you want the business rules prepared -- i.e., typed, single spaced, or handwritten. During the last 15 minutes of class, have students conduct "a conference call" between the director and the consultants ("We forgot to ask about this business need") . Time permitting, have the groups begin to identify entities, attributes, and relationships

What to Watch For Students may not be able to narrow the scope of their design. Help them keep it simple but comprehensive. Use the solution as your guide.

Connections If necessary, review the lesson on Business Rules in Section 4, Lesson 4.



What Will I Learn?

What Will I Learn?



Why Learn It?

Why Learn It?

Why Learn It?

A good starting point would be to write down what you know for sure, what you’re not sure about, and what you don’t know. It helps the team members find out if they all have the same understanding of the problem. It also helps you formulate good follow-up questions for the client. (You want to avoid making a number of calls and asking only a few questions each time. It takes up too much of the client’s time and gives the impression that you are disorganized.)



Tell Me / Show Me

Tell Me / Show Me



Try It / Solve It

Try It / Solve It



Try It / Solve It

Try It / Solve It

Try It / Solve It

Explain to the class that although they can derive some business rules from the interview notes, they will have to guess at some based on their own reasoning and experience. This is where a consultant’s previous experience becomes helpful. Of course, remind them that all business rules will have to be confirmed by the client. The business rules formulated here will be part of their presentation. Remind them that they will be presenting in two days! Some business rules that can be formulated: Structural - Each shelter contains dogs, cats, and the occasional other type of animal (bird, snake). - Basic information taken for all animals: name, age, vaccinations, neuter status, health, reason being given up, and person giving up. If it is a dog, breed and size are noted. If it is a cat, it is classified as long- or short-haired. - Persons who come into the shelter are classified as adopters or nonadopters. Adopters must provide name, address, phone number, email, animal preference, and number of children in the house. - Dog-related mailings must be sent only to dog lovers, and cat related mailings must be sent only to cat lovers.



Procedural - When an animal comes into the shelter, it is assigned an ID and a temporary collar. After the required information is noted, the animal is assigned to a cage. - A nonadopter who comes into the shelter can fill out a card to receive the newsletter. - A list of all unadopted cats and dogs are posted online in the Cat Lovers and Dog Lovers pages of the website.



Lesson 3 - Creating the Animal Shelter ERD

Lesson 3 - Creating the Animal Shelter ERD

Lesson Preparation

Remind students: ERDs get modified over and over until the project is ready to move on to creating the physical database. It's an iterative process in that each time the ERD is reviewed and revised, it more closely approaches the desired result. The ERD is a conversation piece between the client and consultant. It's a guideline for the DBA (database administrator) who will likely implement the consultant's design. It may never be perfect, but hopefully the consultants will take the design a long way toward this goal! Students will make a first pass at their ER models. They will use their interview notes, documented business rules, and assumptions. They will also be introduced to CRUD analysis in this lesson. This technique ties data modeling to functions. Although functional modeling is not covered in this course, students do need to realize that the business functions and processes that the client describes will operate on the data. CRUD analysis checks that all the appropriate operations are possible. This is a good tool to check for completeness and proper scope of the data model.

What to Watch For None.

Connections None.



What Will I Learn?

What Will I Learn?



Why Learn It?

Why Learn It?

Why Learn It?

Tell them that CRUD analysis will be explained in this lesson.



Tell Me / Show Me

Tell Me / Show Me

Tell Me / Show Me

Remind them that a client often describes business functions as part of the scenario. For example: “Whenever we get a new customer, we take down basic information (name, address, email) and assign an ID.” (CREATE) “We’d like to print out a list of songs to be played at each event.” (RETRIEVE) “The event manager reserves the location and may do a site visit. Then she notes down the status and date of each job.” (UPDATE) “A number of our customers were small companies that were hit hard by the recession. They went out of business. We deleted them from our current records.” (DELETE)



Tell Me / Show Me

Tell Me / Show Me

Tell Me / Show Me

Another example you can use is from the DJ business scenario: “Each event is tied to a customer. A customer can ask us to work at many events.” Ask students: Does the ERD have a relationship that reflects this? Answer: Yes, it’s the relationship between CUSTOMER and EVENT and the relationship between JOB ASSIGNMENT and PARTNER.



Tell Me / Show Me

Tell Me / Show Me



Tell Me / Show Me

Tell Me / Show Me

Tell Me / Show Me

Here’s another DJ example that you can use: “We don’t allow customers to transfer ownership of an event to another customer.” This points to a nontransferable relationship, which will disallow updates to certain attributes in the associated entity. In this case, your data model must show a nontransferable relationship between CUSTOMER and EVENT.



Tell Me / Show Me

Tell Me / Show Me

Tell Me / Show Me

You may want to mention that businesses often don’t delete data -- they just flag it as obsolete, or they keep an archive of it. One of the rare occasions that they do want to delete a record from the database is if it’s entered erroneously.



Try It / Solve It

Try It / Solve It

Try It / Solve It You can explain CRUD to the class (they will probably like the acronym) as a way of checking their ERDs.



Try It / Solve It

Try It / Solve It

Try It / Solve It

Assessment: Tell the class that you will be going around to “CRUD” their data models! The answers in the Interview Notes/Business Rule column will vary depending on what they asked during their interview with the client. The key thing is to check for completeness -- do they have all the entities? If they are missing some, remind them of the interview and the data requirements the client provided at that time.



Assessment:



Try It / Solve It

Try It / Solve It

Try It / Solve It

Assessment: Remind the class that each group will be presenting to the “client” during the next meeting. They should start assigning roles and responsibilities for their presentation. If they took good notes during the interview and documented business rules and assumptions, they should have most of the written materials. Check with each team to see what they’re missing. Most will need to do a Statement of the Problem and a Statement of the Proposed Solution. Spend a few minutes giving the class advice on how to organize their presentations. Write the order in which the companies will meet with the client on the board. You can ask for volunteers or write the groups in alphabetical order.



Try It / Solve It

Try It / Solve It

Try It / Solve It

Assessment: Suggested responses: Create -- As new students enter the school, they will need to be added to the database. Retrieve -- The school must retrieve attendance and grade records for specific reports and meetings. Update -- When a student's address, course grade, or parent contact changes, it must be updated. Delete -- After five years, attendance records of students need to be deleted from our records.



Lesson 4 - Presentation to the Animal Shelter Client

Lesson 4 - Presentation to the Animal Shelter Client

Lesson Preparation

This is where the consulting teams meet one-on-one with the client. You may want to have the presentations in front of the class so that the whole group can learn from each group's questions, or you may choose to have the individual groups meet with you in semiprivate so that the latter groups do not have the advantage of hearing the earlier groups' questions. Set a time limit for the one-to-one meeting. As the consultants "tell the story" that the client told them during their initial meeting while showing and explaining the ERD, you (the client) can answer by saying, "Oh no, this is not what I meant!" or "Exactly! You understand exactly what I need.“

What to Watch For None.



Connections Relate to other business situations in which the "expert" must relay information that may not be completely understood by the other party, such as an architect meeting with a potential home buyer, an inventor of a product meeting with a manufacturer, or a computer salesman meeting with an accounting firm. What is the best way for the “experts” to get their message across? Answers include: Pictures! All of these examples would use pictures to better explain the ideas/products.



What Will I Learn?

What Will I Learn?



Why Learn It?

Why Learn It?

Why Learn It?

Point out that if you insist on using technical terms that the client doesn't understand, you will sound just like this mechanic.



Tell Me / Show Me

Tell Me / Show Me

Tell Me / Show Me

Point out that lack of coordination between group members is magnified when you are presenting in front of an audience. The presentation should go smoothly, and everyone should know his or her part. It is also a better use of the client's time to have each person assume a specific role -- for example, one to explain the ERD, one to facilitate questions, one to record information, etc. Allow the groups a few minutes to get ready, and then start the “meetings.”



Try It / Solve It

Try It / Solve It

Try It / Solve It

If a time limit is set for the meetings, be careful not to allow additional questioning after it is over.



Lesson 5 - Final Revisions to the Animal-Shelter ERD

Lesson 5 - Final Revisions to the Animal-Shelter ERD

Lesson Preparation

Students will modify their ERDs based on the feedback from the previous lesson. Remind students that ERDs must be done according to acceptable conventions.

What to Watch For All students should have something to revise. Don't accept the "we're done" too soon. It can always be better with more effort! This illustrates one truth of consulting: "Clients always change their minds!" Again, if the solution looks good, the instructor can ask for something to be different….

Connections Ask students to look for news articles about processes/events that are in the process of being changed -- e.g., "Judge changes trial date based on new evidence." Reinforce the fact that models are often changed or modified during the development process. Remind them of the Dream House activity. What if the client saw the dream house after it had been built? Would it be more expensive to change it then or during the design process?



What Will I Learn?

What Will I Learn?

What Will I Learn?

The changes you ask for will vary from group to group. Some may have a model that is significantly different from the proposed solution. They may not have an ADOPTION RECORD entity because they did not recognize the relationship (M:M) between ANIMAL and PERSON. Remind them that an animal may be returned back to the shelter and adopted by another person. Some groups may have made CAGE NUMBER an attribute of ANIMAL because they did not see the need to track CAGE OCCUPANCY history. Tell them that there have been times when finding an animal has been difficult because it has been moved from one cage to another. Having a CAGE OCCUPANCY history will help trace where the animal was. If their model is quite close to the proposed solution, you can ask for small changes, such as adding an attribute to track additional information (e.g., ANIMAL weight). More suggestions for changes are listed in the teacher instructions for the activity.



Why Learn It?

Why Learn It?



Tell Me / Show Me

Tell Me / Show Me

Tell Me / Show Me

Remind students that changes and additions are very much a part of the system development process. As discussed in the very first lesson on conceptual modeling, it is easier to make changes to the conceptual model than to have to implement it later down the line. Consultants need to be flexible and patient. This is a skill that all clients appreciate.



Try It / Solve It

Try It / Solve It

Try It / Solve It

Remind students that as they redraw the model, they should make sure they are following good drawing and labeling conventions. We want the model to be clearer, not more confusing. Some suggestions for changes to make: Need to track animal weight (new attribute in ANIMAL) Need to track what people are allergic to (if just one allergy, then this can be an attribute in PERSON; otherwise, you will need an ALLERGY entity in a M:M relationship with PERSON) Need to track if PERSON wants to receive newsletter (an attribute of the supertype PERSON) Need to track if a CAT has been declawed (an attribute of the CAT subtype) You can also ask for general changes to make the diagram more readable: More “white space” so that relationship names don’t bump up against each other No criss-crossing relationship lines More efficient use of space (entities with few attributes should be smaller than entities with more attributes) Mandatory and optional attributes indicated with “*” and “o”; UIDs indicated with “#”

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