Week Two Entity Relationship Diagram. Marlon R. Evans DBM/502 3/27/17. Mark Paxton

Transcription

1 Week Two Entity Relationship Diagram Marlon R. Evans DBM/502 3/27/17 Mark Paxton File Name: Evans WK2 - E-R Diagram.doc Microsoft Word Statistics for your paper: Total Number of Pages Found in Full Document = 3 Total Number of Characters Found in Full Document = 1,748 Total Number of Lines Found in Full Document = 43 Total Number of Words Found in Full Document = 323 Other: Words = 316 Characters = 1714 Paragraphs = 21 Sentences = 16 Sentences per Paragraph = 2.2 Words per Sentence = 16.1 Characters per Word = 5 Passive Sentences = 0 Flesch Reading Ease = 41.5 Flesch-Kincaid Grade Level = 11.4

2 2 Entity Relationship Diagram When you see APA Format as the requirement, always think INTRO/BODY/CONCLUSION. What follows is part of the body of the paper without an introduction. I split the assignment 50/50 between the paper and the ERD to give students some leeway on the assignment so that they can do reasonably well on the assignment, so for next week pay attention to both aspects of the assignment. Entity names are shown on the top and relationships are shown along with cardinalities, primary keys attributes and foreign keys. As part of normalization, entities like SolarPanelAtChargingSpace and EquipmentsAtChargingSpace were created to store relationship data. Entities were identified and put as separate entities. You are missing a clear introduction/thesis. The introduction is where you set the stage for what follows. Generally, your papers will benefit from stronger

3 3 introductions. The introduction indicates what the paper will be about and how you will approach the topic. For more information, refer to the 5-paragraph tutorial from Writing Wizards in the Tutorials & Guides section of the Center for Writing Excellence for more information about writing introductions. The CWE (Center for Writing Excellence) also has a THESIS GENERATOR you might want to look at. While preparing the database to use, first step is to enter information about location, garages and charging spaces. This is the foremost and urgent requirement. Inserting the data for this activity uses following entities/tables: - Location - Garage - ChargingSpace - Equipment - SolarPanel - SolarPanelAtChargingSpace - EquipmentsAtChargingSpace The entity ElectricityCharges can be updated on a regular interval to store electricity rates. Likewise following tables can be updated to store information if any equipment is not working or to store current power level of solar panel: - SolarPanelAtChargingSpace - EquipmentsAtChargingSpace Customer information can be updated as soon as customer is identified. Reservation for a charging space can be made using table Reservation. Denormalization may be used to decrease the running time of select queries by making data more accessible to the queries or by generating summarized reports in separate tables. This

4 4 process can bring some new problems like the updating/deletion and insertion as data is duplicated. To speed up performance of the queries, Indexes can be used. Indexes are special lookup tables that the database search engine can use to speed up data retrieval. Simply put, an index is a pointer to data in a table. An index in a database is very similar to an index in the back of a book. However, overuse or incorrect usage can negatively impact performance. Citing a source here would have provided you with some of these facts and made your statements/position defendable. In the given database model, indexes can be created on few columns to speed up report generation. For example, to get a report which shows the rate on a particular time range, indexes can be created on columns FromHour and ToHour as these will be used in where clause of the queries. Your paper would have benefited from a conclusion. A concluding paragraph summarizes the main idea, ties the main points together neatly for the reader (what you promised the reader in the introduction), and ends with a sense of finality. Generally, you should avoid introducing new ideas in the conclusion. Missing Reference List (always a requirement for an APA paper) Content / Development (70%) Points Earned Comments ASSIGNMENT. All key elements of the assignment are covered in a substantive manner: Review the materials you have, describing the information to be captured and the overall project. Create an Entity-Relationship diagram for the information you will need. Be sure to clearly name the entities and the relationships. Include and indicate the primary key attributes, as well as any foreign keys, or other attributes implied by the materials. Determine and 2.38 See comments

5 5 indicate the cardinality of each relationship. (Please take the time to be clear on what an Entity-Relationship diagram is; on occassion, I receive inexplicable drawings from students that are not E-R diagrams. I will also caution you that creating a correctly completed E-R diagram is a nontrivial exercise, which means unless you are already highly skilled in this, you will spend a meaningful amount of time on the design and diagram.) Provide a normalized version of the diagram in at least Third Normal Form. Note that for anyone familar with Microsoft Access, do not use this tool to create the tables and attributes to render the diagram. There are several reasons that this is inappropriate, the least of which is that Microsoft Access will not always render a true or correctly depicted E-R diagram and it will not be accepted. Explain the reason for any model changes you made as part of the normalization. Specify how entities, relationships, and their attributes will be represented. Consider the common and urgent activities that will access this information. Explain where you might use denormalization, indexing, or other techniques to improve performance for these operations, and why. Combine all items and submit in an APA formatted paper. This means, your E-R diagram should be inserted into the document as a part of the Microsoft Word document submitted for the assignment (and that you can use any tool of your choosing to create the E-R diagram. (However, don't try to hand draw the E-R diagram using Microsoft PowerPoint. You can easily find tools for creating true E- R diagrams. For example, Microsoft Visio (if you have access to this), or if if you wish to use a free tool Google Draw supports E-R diagraming. There are others as well.) Submit your assignment using the Assignment Files tab. [] The content is comprehensive, accurate, and /or persuasive. [] The paper develops a central theme or idea, directed toward the appropriate audience. [] The paper links theory to relevant examples of current experience and industry practice and uses the vocabulary of the theory correctly. [] Major points are stated clearly; are supported by specific details, examples, or analysis; and are organized logically. [] The introduction provides sufficient background on the topic and previews major points. [] The conclusion is logical, flows from the body of the paper, and reviews the major points. See comments Readability and Style (15%) [] Paragraph transitions are present and logical and maintain the flow throughout the paper. [] The tone is appropriate to the content and assignment. [] Sentences are complete, clear, and concise. [] Sentences are well-constructed, with consistently strong, varied sentences. Points Earned 0.49 See comments Comments

6 6 [] Sentence transitions are present and maintain the flow of thought. Mechanics (15%) Points Earned Comments [] The paper, including the title page, reference page, tables, and appendices, follow APA guidelines for format. [] Citations of original works within the body of the paper follow APA guidelines. [] The paper is laid out with effective use of headings, font styles, and white space. [] Rules of grammar, usage, and punctuation are followed. [] Spelling is correct See comments Total Points Earned 3.17 Key to Comments in body of paper: Entries in RED are items that most likely have affected your grade (positively or negatively); they consist of error corrections, grammar problems, as well as supporting comments. Entries in BLUE are typically Comments (e.g., my observations on the topic, suggestions for improvement, and comments on what you have written; in short, they don't directly relate to the grade). YELLOW highlights may highlight a section for comment or may be used like a check mark, although you may see check marks as well. PINK/PURPLE highlights mean that there is an issue with what was highlighted and it will relate to the points earned. Normally there will be an accompanying comment, unless the issue is fairly obvious (e.g., misspelled words, or the error has already been commented on elsewhere in the paper). Ask, if you cannot determine what the reason was. GREEN highlights are typically used to match up citations in the body to entries in the reference list. GRAY highlights usually are for my purposes to highlight a keyword in your paper (or to point out to you overuse of a single word/phrase). You might also see BLUE highlights used to highlight direct quotes (which most writing guides advise to use sparingly). I try to be consistent, however, if ever in doubt, please do ask if you are unclear. Days Late 4 Adjusted Score 1.57 ERD Design (4 points) 3.4 Decent first effort - it is an iterative process and the first design is seldom 100%; you can see how incredibly complex a design can get by looking at the feedback and considering how many of the actual requirements the first design does not address Late Penalty 1.8 Total Points for Assignment 3.37

7 7

8 Does not appear to be tracking utility prices over time (remember our discussion on the use of effective dates?) without effective dates, you have no way to create the reports noted in the requirements your table only allows for one rate to be in effect at any time. -How do you identify quick charge slots? -Unclear what you mean by iscontinuing in Reservation table. Since your Reservation is by Customer, there is really need for one status attribute that tells you whether the reservation is valid, cancelled, or close out (as in the past and paid for). Unclear why you felt the need to create a LOCATION table; the locational information for the Garage is functionally determined by the Garage and by virtue of how you set up the FK the relationship between the two tables should be one-to-one (which you do not depict). How did you imagine a Location having more than one garage (and why)? What is isreserved in ChargingSpace? If this is tracking whether there is a reservation for the space, it would not work well for you. Do not see anywhere that you are tracking the amount of electricity being generated by the solar panels versus power company consumption.