CS157a Spring 2002Practice Midterm 1

The practice midterm is below. Here are some facts about the actual midterm: (a) The midterm will be in class . (b) It is closed book, closed notes. Nothing will be permitted on your desk except your pen (pencil) and test. (c) You should bring photo ID. (d) There will be more than one version of the test. Each version will be of comparable difficulty. (e) If your cell-phone or beeper goes off you will be excused from the test at that point and graded on what you have done till your excusal. (f) One problem (less typos) on the actual test will be from the practice test.

 1. Define the following DB terms and give an example:
   (a) parametric user
   (b) DDL
   (c) catalog
   (d) composite attribute
   (e) controlled redundancy

2. Suppose we have the following entity set E for some entity type:
       { e_1= (a,b,c,d)
         e_2= (a,f,g,h)
         e_3= (b,i,g,h) }
   List all possible keys.

3. For each of the following binary relationships suggest possible
   cardinality ratios. Explain your reasoning:

   (a) [Airplane type]---<can land>---[Airport]
   (b) [Patient]---<checks in>---[Hospital Ward]
   (c) [Ship]---<home port is>---[Port] 
   (d) [Book]---<loaned to>---[Member]
   (e) [Department]---<controls>---[Project]

4. Imagine you are responsible for designing an on-line dating service
   like Match.com. Come up with an ER diagram which models this situtation.
   List all your assumptions.

5. Explain the three-schema architecture for DBMS's. Describe each of the
   levels.

6. Describe four different kinds of DB interfaces.
           
7. For each of the following situations say if the participation or 
   completeness constraint is total or partial. Give your reasoning.
 
   (a) a weak entity type in its identifying relation 

   (b) a user defined subclass of a superclass

   (c) subclasses of a superclass satisfying a disjointness constraint

   (d) an entity participating in a 1:1 relationship

8. Null values in a relationship can mean several things. Give three
   different meanings and an example of each.

9. Distinguish between the following concepts: stored versus derived attribute,
   single-valued vs multivalued attribute.

10. Subclasses inherit what properties from superclass entity types in the EER
    model?