The minimum requirement for active attendance: 3 tasks done
1. The ER diagram for the Company database is given in E&N2, p. 58 (E&N3, p. 65). a) Consider a variant of the diagram where the dependents of an employee are represented as a (multi-valued) attribute of the employee. What changes this would cause for the corresponding relational database schema? b) Consider the situation where the dependents can be identified using their own social security numbers. How the ER diagram and the relational database diagram would change? 2. Explain the meaning of the following ER schemas and give the relational database schemas (with integrity constraints) corresponding to the ER schemas (E&N2, p. 61, Figure 3.16 a & c; E&N3, p. 97, Fig. 4.13 a & c). 3. Explain the meaning of the following ER schema and give the relational database schema (with integrity constraints) corresponding to the ER schema (E&N2, p. 68; E&N3, p. 70). 4. Suppose the relational database schema Person(SSN, FirstName, LastName), Dead(SSN, DeathDate), MarriedCouple(HusbSSN, WifeSSN, WeddingDate), Divorced(HusbSSN, WeddingDate, DivorceDate). Write the following queries in relational calculus: a) The names of Melanie Griffith's husbands and the associated wedding dates. b) The names of living persons. c) The names of living married men. 5. Write thw following queries in domain relational calculus (the well-known Company database): a) The social security numbers of those managers whose departments are active in Houston or Stafford. b) The names of those departments that do not have activities at every location of the company. c) The names of those departments that have activities at every location of the company.