DBMS - Interview Questions and Answers
Explain the difference between total specialization and partial specialization.
Total specialization exists when every instance of a supertype must also be an instance of a subtype. Partial specialization exists when every instance of a supertype does not have to be an instance of a subtype.
Explain the difference between an ERD and EER.
An EER includes everything in an ERD and an EER allows for more complex relationships than an ERD. An EER allows for object-oriented data modeling and include supertypes and subtypes entities and inheritance.
Explain the difference between the disjoint and overlap rule.
The disjoint rule states an entity instance of a supertype can only be a member of one subtype. The overlap rule states an entity instance of a supertype can be a member of multiple subtypes.
List the three types of business rules and define each of them.
A derivation is a statement that is derived from other knowledge. A structured assertion is a statement that expresses some aspect of the static structure of an organization. An action assertion is a statement of a constraint on the actions of an organization.
Explain how a scenario is used for business rules.
A scenario is used to test business rules. It is a short script that describes how a business reacts to certain situations.
Explain some of the main goals of normalization.
Normalization should minimize data redundancy. It should also simplify referential integrity constraints. Normalization will also make it easier to insert, update, and delete data. And finally, it provides better design.