Why do we designate one of the candidate keys of a relation to be the pri- mary key? Discuss the characteristics of relations that make them different from ordi- nary tables and files. Discuss the various reasons that lead to the occurrence of NULL values in relations.
Define the following terms as they apply to the relational model of data: domain, attribute, n-tuple, relation schema, relation state, degree of a rela- tion, relational database schema, and relational database state. Why are tuples in a relation not ordered? Why are duplicate tuples not allowed in a relation? What is the difference between a […]