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FORDHAM UNIVERSITY, Fordham College Lincoln Center

CSEU 3500 -- Data Base Systems

Dept. of Computer & Info. Sciences, Spring, 2004

CSEU 3500 -- Data Base Systems

Dept. of Computer & Info. Sciences, Spring, 2004

Note: Questions marked with an asterisk are significantly different from the corresponding questions in the text. Relatively minor clarifications and additions to the other questions are in brackets.

**7.4**- [
*10 pts.*] List all the functional dependencies satisfied by the relation of Figure 7.21. [Do not include trivial dependencies or those with extraneous variables. Justify your answer.]

Figure 7.21 Relation of Exercise 7.4 **7.6**- [
*10 pts.*] Explain how functional dependencies can be used to indicate the following [mapping cardinality constraints. That is, state what functional dependencies would, if satisfied by a database, guarantee that the cardinality constraints are obeyed.]- A one-to-one relationship set exists between entity sets
*account*and*customer*. - A many-to-one relationship set exists between entity sets
*account*and*customer*.

*account*is*account-number*and the primary key of*customer*is*customer-name*.] - A one-to-one relationship set exists between entity sets
**7.7**- [
*5 pts.*] Consider the following proposed rule for functional dependencies: If and then . Prove that this rule is*not*sound by showing a relation which satisfies and but does not satisfy . **7.11***- [
*25 pts.*] [Draw the functional-dependency diagram (as described in class)] for the following set of functional dependencies for the relation scheme . Compute the closure of . [Omit trivial dependencies or those with extraneous variables.][1] [2] [3] [4] [5] Set of functional dependencies. **7.12***- [
*10 pts.*] Using the functional dependencies of Exercise 7.11, compute . **7.13***- [
*10 pts.*] Given the schema and functional dependencies of Exercise 7.11, show that the following decomposition of is a lossless-join decomposition:

**7.16***- [
*10 pts.*] Show that the following decomposition of the schema of Exercise 7.11 is not a lossless-join decomposition:

*Hint:*Give an example of a relation on [satisfying the set of functional dependencies] such that

Robert Moniot 2004-04-26