CS 4604 Course Project: Step 3

Date Assigned: September 25, 2002
Date Due: October 2, 2002

Before you answer the following questions, write a one-paragraph summary of what your project application domain is (in other words, remind us of your project and what you promised to do in it). Also, for those of you for whom we had comments and suggestions about your Step 2 (about corrections to be made to your E/R and/or ODL designs), address those modifications first before you start with Step 3. If you already start with a flawed design (or if our feedback comments from Step 2 are not incorporated), no credit will be given for Step 3!!!! If you have any questions, meet the instructor or the TA during their office hours with the graded Step 2 and they will help you to address the modifications suggested.
  1. (40 points) Go back to the ODL schema from Step 2. Use the method taught in class and convert from ODL to relations (This is also described in your textbook). Do not circumvent this step or try to get creative here! Just do a plain, simple, conversion from ODL to relations (Your solution will be graded on how effectively you are able to do this transformation; not on the quality of the final output relations). Recall that every class gets its own relation and every relation *has* to come from a class. Relationships *do not* get their own relation. Follow strictly this procedure; do not attempt to be creative! Underline key attributes in your relation schema. Your answer should consist of several lines of the form: 
    
Relation1(attr1,attr2,attr3,...,attrn)
....
    Attach a copy of your ODL schema.

  2. (40 points) Likewise, convert from your E/R diagram to relations. Again, strictly follow the procedures taught in class (and described in the textbook). Remember that each entity set gets its own relation and so does every relationship (unlike ODL, this means you will typically have more relations than from ODL). Follow strictly the procedure taught in class; do not attempt to be creative! For your solution, submit just a list of relation schemas (i.e., the names of the relations and what their attributes are). Attach a copy of your E/R diagram to your answer. As always, underline key attributes.

    For both of the above, if you have inheritance, use the technique described in Section 3.3.2 for converting from ODL, and the one described in Section 3.3.1 for converting from E/R. Please do not use the technique of Section 3.3.3 (even though it is more succinct) since that will not help you to answer the next question.
  3. (20 points) Which one of these schemas do you think is the better one? (in terms of reducing redundancy, and preventing anomalies) Why? So, which do you think is preferable - starting from ODL or starting from E/R?
What to turn in: Paper copies of these answers. Please include the E/R diagram and the ODL code, so that we can verify that you did the conversion correctly. Identify your group by your project title and the team members. Also note that this is supposed to be a joint effort: so, discuss and identify any constraints and restrictions that your domain poses.

FAQ: Well, the relations from ODL ain't look that good. Don't I need to normalize these relations?

Answer: You don't need to. That will form Step 4 of your project. You will have plenty more opportunities to do that.

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