DATABASE MANAGEMENT SYSTEMS

ASSIGNMENT - III

(QUESTIONS FROM PREVIOUS PAPERS)

1. What is the goal of query optimization?. Why it is important?

2. Describe various fundamental operations that are available in relational algebra. give suitable examples for each of them.

3. Write short notes on i) Translating SQL queries

                                       ii) Relational Algebra Equivalences.

 4. Explain Natural join with example.

5. Define the term most selective acees path for a query.

6. Explain selection, projection, join and set operations with examples to query processing.

7. Explain multiple relation query optimization with suitable examples.

8. What is query processing. Explain.

9. Write about join strategies.

10. Explain nested sub queries in SQL with suitable examples.

11. Let R=(A,B,C) and let r1 and r2 both are relations on schema R. Give an expression in SQL that is equivalent to each of the following queries:-

              i)  r1  U r2

            ii) r1  -  r2

            iii) pi(A,B) (r1) JOIN pi(B,C) (r2).