CS145 Assignment #6

Due Wednesday Nov. 17, 1999

Step 6 of Your PDA

This part involves object-relational features of Oracle 8. You should refer to the Oracle Objects Guide as needed.

  1. (20 pts.) Declare some data types that could be used with the data of your PDA. You need to choose types such that:

    Show your declarations (don't forget type bodies when there are methods) and the successful compilation of the declarations. Remember that the slash is needed to cause compilation.

  2. (20 pts.) Declare some relations that could hold data associated with your PDA. Choose relations so that:

    Note that it is possible for one relation to satisfy all these conditions. Write INSERT statements to populate your new relations from the data in the original relations of your PDA. Show the correct compilation of your declaration and correct execution of your insertion statements.

    Aside: The most recent release of the Oracle loader allows object-relations to be populated directly. However, this loader is not yet running at Stanford, so we have to populate object-relations in this kludgy way.

  3. (20 pts.) Write 4 or more queries on your relations from (2). Among these queries, you should demonstrate the following features at least once:

Problem Set

  1. (25 pts.) Suppose we have the following attributes: C (course), T (teacher), H (hour), R (room), S (student), and G (grade), with the following functional dependencies: C->T, CS->G, HR->C, HT->R, HS->R, CH->R, HS->C, and HRS->T. Note that these FD's allow us to assume that a course may meet in different rooms at different hours. The interpretation of the first three are ``a course has only one teacher,'' ``a student gets only one grade in a course,'' and ``only one course can be in a room at any one time.'' The others have similar interpretations that follow from ``physics''; e.g., students and teachers cannot be in two places at once.

    The first five FD's are one minimal set of FD's. Find another minimal set. Show your reduction steps.

    Give a decomposition of the schema CSGHRT into 3NF schemas that have a lossless join and preserve FD's.

    If we project the relation CSGHRT onto the set of attributes CHRT, and project the given FD's, what are the keys for CHRT?

    Are there any BCNF violations for CHRT? Give an example, if so.

    Are there any 3NF violations for CHRT? Give an example, if so.

  2. (15 pts.) Suppose we have a relation schema ABCD and the dependencies A->->B and B->C (i.e., A multidetermines B, while B functionally determines C). Which of the following dependencies must hold? For each, either give a reason why, or give a counterexample relation instance for ABCD.