table name and column name are used to help in interpreting the meaning of volumes of each row. Each row of table is called a data record. Questions for Practice Short Answers . State main categories of data models.
. How are computers useful in processing the accounting data? . What do you understand by accounting data?
Discuss the stages through which it is finally transformed for being presented as information in financial statements. . What do you understand by database. How does it differ from DBMS?
. What is meant by entity type? How it is different from entity set? Illustrate by giving suitable example from accounting reality.
. What do you understand by relationship type? How is it different from relationship instance and relationship set? .
What do you understand by multi-valued attribute? How is it different from complex and composite attribute? Illustrate by giving suitable example. .
What do you understand by the concept of weak entity used in data modelling? Explain the relevance of owner entity type, partial key and identifying relationship in the context of such modelling. . What is a participation role?
State the circumstances under which the use of role names becomes necessary in description of relationship types. . Define foreign key. How is this concept useful in relational data model?
Illustrate with suitable example. . What is meant by NULL value? What are the reasons that lead to their occurrence in database relations?
. Why are duplicate tuples not allowed in a relation? . What do you understand union compatibility of relations?
For which operations such compatibility is required and why? . What is the need for database normalisation? Long Answers .
Discuss the basic concepts of Entity Relationship (ER) Model. Illustrate as to how an ER model is diagrammed. . What integrity constraints are specified on database schema?
Why is each considered important? . Discuss the different types of update operations in relation to the integrity constraints which must be satisfied in a relational database model. .
Discuss the steps you would take to transform an ER Model into various relations