CP5633 Database Modelling Assignment 1- ERD Modelling

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1 Assignment ERD Modelling CP5633 Database Modelling Assignment - ERD Modelling Assignment worth: 20% Due date: week 6 Friday, 23rd of December Note: This is an individual assignment. While it is expected that students will discuss their ideas with one another, students need to be aware of their responsibilities in ensuring that they do not deliberately or inadvertently plagiarize the work of others. Rationale This assignment has been designed to assess your ability to model data, by constructing an entity-relationship diagram for a particular business scenario. This assignment addresses the following learning objectives for this subject: Perform conceptual modelling using Entity-Relationship Diagrams (ERDs) Discuss business assumptions which affect data modelling. Model a database using the entity-relationship (ER) model and understand the database development process Use the techniques of normalization Tasks. You are to write a brief discussion of your solution, i.e. how you approached the modelling problem and any issues you may have encountered (maximum of ½ page). 2. You are to write all applicable business rules necessary to establish entities, relationships, optionalities, connectivities, cardinalities and constraints. If a many to-many relationship is involved, state the business rules regarding the bridging entities after breaking down the many-to-many relationship. An example business rules format can be found in the Appendix of this document. Business rules you write are expected to be in the same format as presented in the Appendix. 3. Based on these business rules,* draw a fully labelled and implementable Entity-Relationship Diagram (ERD). Include all entities, relationships, optionalities, connectivities, cardinalities and constraints. You must use Crow s foot notation and MS Visio to create the ERD (a hand-drawn ERD will NOT be accepted). A sample ERD can be found in the Appendix of this document. (Note: The ERD created using Visio will need to be saved as an image file and then be included in your document file to be submitted). Page of 9

2 Assignment ERD Modelling 4. A summary to describe the major justifications, assumptions and limitations related to your database design. For example: a. Assumption/justifications for optionalitiy, connectivities, constraints data type and data domain; and b. Special cases or data integrity issues that cannot be handled. Note: Designing the database is an iterative process; you may find yourself going back and forth between Tasks and 3 to revise the design. Make sure that your final submission shows consistent design in the business rules and ERD. Submission You need to submit a document file (MS Word format) to LearnJCU; this document should include all the answers for tasks -4. Please name the file as LastnameFirstnameA.doc. You need to also submit the MS Visio file containing the ERD. Timestamp shown on LearnJCU assignment submission will be used to determine if the assignment is late or not. Refer to the subject guide for the policy for late submission. Page 2 of 9

3 Assignment ERD Modelling Business Description Global Computer Solutions (GCS) is an information technology consulting company with many offices located throughout Australia. The company s success is based on its ability to maximize its resources that is, its ability to match highly skilled employees with projects according to region. To better manage its projects, GCS has contacted you to design a database so that GCS managers can keep track of their customers, employees, projects, project schedules, assignments and invoices. The GCS database must support all of GCS s operations and information requirements. A basic description of the main entities follows: The employees working for GCS have an employee ID, an employee last name, a middle name initial, a first name, a region where he/she works, and a date of hire. Valid regions are as follows: Northwest (NW), Southwest (SW), Midwest North (MN), Midwest South (MS), Northeast (NE), and Southeast (SE). Each employee has many skills, and many employees have the same skill. Each skill has a skill ID, description, and rate of pay. Valid skills are as follows: data entry I, data entry II, systems analyst I, systems analyst II, database designer I, database designer II, Cobol I,, C++ I, C++ II, VB I, VB II, ColdFusion I, ColdFusion II, ASP I, ASP II, Oracle DBA, MS SQL Server DBA, network engineer I, network engineer II, web administrator, technical writer, and project manager. The table below shows an example of the Skills Inventory. Skill Data Entry I Data Entry II Systems Analyst I Systems Analyst II I Cobol I C++ I Employee Seaton Amy; Williams Josh; Underwood Trish Williams Josh; Seaton Amy Craig Brett; Sewell Beth; Robbins Erin; Bush Emily; Zebras Steve Chandler Joseph; Burklow Shane; Robbins Erin Yarbrough Peter; Smith Mary Yarbrough Peter; Pascoe Jonathan Kattan Chris; Epahnor Victor; Summers Anna; Ellis Maria Kattan Chris; Epahnor Victor, Batts Melissa Smith Jose; Rogers Adam; Cope Leslie Page 3 of 9

4 Assignment ERD Modelling C++ II VB I VB II ColdFusion I ColdFusion II ASP I ASP II Oracle DBA SQL Server DBA Network Engineer I Network Engineer II Web Administrator Technical Writer Project Manager Rogers Adam; Bible Hanah Zebras Steve; Ellis Maria Zebras Steve; Newton Christopher Duarte Miriam; Bush Emily Bush Emily; Newton Christopher Duarte Miriam; Bush Emily Duarte Miriam; Newton Christopher Smith Jose; Pascoe Jonathan Yarbrough Peter; Smith Jose Bush Emily; Smith Mary Bush Emily; Smith Mary Bush Emily; Smith Mary; Newton Christopher Kilby Surgena; Bender Larry Paine Brad; Mudd Roger; Kenyon Tiffany; Connor Sean GCS has many customers. Each customer has a customer ID, customer name, phone number, and region. GCS works by projects. A project is based on a contract between the customer and GCS to design, develop, and implement a computerized solution. Each project has specific characteristics such as the project ID, the customer to which the project belongs, a brief description, a project date (that is, the date on which the project s contract was signed), a project start date (an estimate), a project end date (also an estimate), a project budget (total estimated cost of project), an actual start date, an actual end date, an actual cost, and one employee assigned as manager of the project. The actual cost of the project is updated each Friday by adding that week s cost (computed by multiplying the hours each employee worked by the rate of pay for that skill) to the actual cost. The employee who is the manager of the project must complete a project schedule, which is, in effect, a design and development plan. In the project schedule (or plan), the manager must determine the tasks that will be performed to take the project from beginning to end. Each task has a task ID, a brief task description, the task s starting and ending date, the type of skill needed, and the number of employees (with the required skills) required to complete the task. General tasks are initial interview, Page 4 of 9

5 Assignment ERD Modelling database and system design, implementation, coding, testing, and final evaluation and sign-off. For example, GCS might have the project schedule shown in the table below. Project ID: Description: Sales Management System Company : See Rocks Contract : 2/2/204 Region: NW Start : 3//204 End : 7//204 Budget: $5,500 Start End Task Description Skill(s) Required Quantity Required 3//4 3/6/4 Initial Interview Project Manager Systems Analyst II 3//4 3/5/4 Database Design 3//4 4/2/4 System Design Systems Analyst II Systems Analyst I 2 3/8/4 3/22/4 Database Implementation Oracle DBA 3/25/4 5/20/4 System Coding & Testing Cobol I Oracle DBA 2 3/25/4 6/7/4 System Documentation Technical Writer 6/0/4 6/4/4 Final Evaluation Project Manager Systems Analyst II 6/7/4 6/2/4 On-Site System Online and Data Loading Project Manager Systems Analyst II 7//4 7//4 Sign-Off Project Manager Assignments: GCS pools all of its employees by region, and from this pool, employees are assigned to a specific task scheduled by the project manager. For example, for the first project s schedule, you know that for the period 3//4 to 3/6/4, a Systems Analyst II, a Database Designer I, and a Project Manager are needed. (The project manager is assigned when the project is created and remains Page 5 of 9

6 Assignment ERD Modelling for the duration of the project). Using that information, GCS searches the employees who are located in the same region as the customer, matching the skills required and assigning them to the project task. Each project schedule task can have many employees assigned to it, and a given employee can work on multiple project tasks. However, an employee can work on only one project task at a time. For example, if an employee is already assigned to work on a project task from 2/20/4 to 3/3/4, (s)he cannot work on another task until the current assignment is closed (ends). The date on which an assignment is closed does not necessarily match the ending date of the project schedule task, because a task can be completed ahead of or behind schedule. Given all of the preceding information, you can see that the assignment associates an employee with a project task, using the project schedule. Therefore, to keep track of the assignment, you require at least the following information: assignment ID, employee, project schedule task, date assignment starts, and date assignment ends (which could be any dates as some projects run ahead of or behind schedule). The next table shows a sample assignment form. Project ID: Description: Sales Management System Company: See Rocks Contract : 2/2/200 As of: 03/29/0 SCHEDULED ACTUAL ASSIGNMENTS Project Task Start End Skill Employee Start End Initial Interview 3//4 3/6/4 Project Mgr. Sys. Analyst II 0 Connor S. 02 Burklow S. 03 Smith M. 3//4 3//4 3//4 3/6/4 3/6/4 3/6/4 Database 3//4 3/5/4 04 Smith M. 3//4 3/4/4 Design System Design 3//4 4/2/4 Sys. Analyst II Sys. Analyst I Sys. Analyst I 05 Burklow S. 06 Bush E. 07 Zebras S. 3//4 3//4 3//4 Database 3/8/4 3/22/4 Oracle DBA 08 Smith J. 3/5/4 3/9/4 Implementation System Coding & Testing 3/25/4 5/20/4 Cobol I Cobol I 09 Summers A. 3/2/4 3/2/4 Page 6 of 9

7 Assignment ERD Modelling Oracle DBA 0 Ellis M. Ephanor V. 3/2/4 3/2/4 2 Smith J. System 3/25/4 6/7/4 Tech. Writer 3 Kilby S. 3/25/4 Documentation Final Evaluation 6/0/4 6/4/4 Project Mgr. Sys. Analyst II On-Site System Online and Data Loading 6/7/4 6/2/4 Project Mgr. Sys. Analyst II Sign-Off 7//4 7//4 Project Mgr. (Note: The assignment number is shown as a prefix of the employee name; for example: 0, 02.) Assume that the assignments shown previously are the only ones existing as of the date of this design. The assignment number can be whatever number matches your database design. The hours an employee works are kept in a work log containing a record of the actual hours worked by an employee on a given assignment. The work log is a weekly form that the employee fills out at the end of each week (Friday) or at the end of each month. The form contains the date (of each Friday of the month or the last work day of the month if it doesn t falls on a Friday), the assignment ID, the total hours worked that week (or up to the end of the month), and the number of the bill to which the work log entry is charged. Obviously, each work log entry can be related to only one bill. A sample list of the current work log entries for the first sample project is shown in figure below. Employee Name Week Ending Assignment Number Hours Worked Bill Number Burklow S. 3// xxx Connor S. 3//4-0 4 xxx Smith M. 3// xxx Burklow S. 3/8/ xxx Page 7 of 9

8 Assignment ERD Modelling Connor S. 3/8/ xxx Smith M. 3/8/ xxx Burklow S. 3/5/ xxx Bush E. 3/5/ xxx Smith J. 3/5/ xxx Smith M. 3/5/ xxx Zebras S. 3/5/ xxx Burklow S. 3/22/ Bush E. 3/22/ Ellis M. 3/22/4-0 2 Ephanor V. 3/22/4-2 Smith J. 3/22/ Smith J. 3/22/4-2 2 Summers A. 3/22/ Zebras S. 3/22/ Burklow S. 3/29/ Bush E. 3/29/ Ellis M. 3/29/ Ephanor V. 3/29/4-35 Kilby S. 3/29/ Smith J. 3/29/ Summers A. 3/29/ Zebras S. 3/29/ (Note: xxx represents the bill ID. Use the one that matches the bill number in your database.) Finally, every 5 days, a bill is written and sent to the customer, totalling the hours worked on the project that period. When GCS generates a bill, it uses the bill number to update the work-log entries that are part of that bill. In summary, a bill can refer to many work log entries, and each work log entry can be related to only one bill. GCS sent one bill on 3/5/0 for the first project, totalling the hours worked between 3//0 and 3/5/0. Therefore, you can safely assume that there is only one bill in this table and that that bill covers the work-log entries shown in the form. Page 8 of 9

9 Assignment ERD Modelling APPENDIX: SAMPLE BUSINESS RULES & ERD Sample Business Rules: Each SCHOOL has at least ten or many STUDENTs. Each SCHOOL has one or many SUBJECT. Each STUDENT can take many SUBJECTs. o Each STUDENT has one or many ENROLMENT records. o Each ENROLMENT record is related to one STUDENT. Each STUDENT is associated with one SCHOOL. A STUDENT is resident of one CITY. Each SUBJECT is offered by one SCHOOL. Each SUBJECT has zero or many STUDENTs. o Each SUBJECT has zero or many ENROLMENT records. o Each ENROLMENT record is related to one SUBJECT. Each CITY has zero or many STUDENT lived in it. Each CITY is in one COUNTRY. Example ERD Format Page 9 of 9

Database Systems: Design, Implementation, and Management Tenth Edition. Chapter 4 Entity Relationship (ER) Modeling

Database Systems: Design, Implementation, and Management Tenth Edition Chapter 4 Entity Relationship (ER) Modeling 4.1 The Entity Relationship Model (ERM) ER model forms the basis of an ER diagram ERD