INF503 WEEK-6 LESSON (18,20&21) LAB

 LESSON 18

1. Which search applies to any file, but all the other methods depend on having the appropriate access path on the attribute used in the selection condition?

A) .linear

2. . In which of the following joins does the search stop as soon as the first match is found and the tuple from outer relation is selected?

A) .Semi-join

3 Which of the following methods ends the iteration after all tuples that can be generated have been generated

A). Close()

LESSON 20

1. What will a transaction be called, if the database operations in a transaction do not update the database but only retrieve data?

A). Read-only

2 . In which of the following states does a transaction execute its READ and WRITE operations

A) . Active

LESSON 21

1.    Which of the following locks is too restrictive for database concurrency control purposes?

A) . Binary

2.    Which two-phase locking protocol is a deadlock-free protocol?

A) .Conservative

3 . Which phase of concurrency control checks whether any of the transactions violate serializability?

A ). Validation

LAB .18

1.

2.

SELECT COUNT(DISTINCT Dnumber)
FROM EMPLOYEE_REC E, EMPLOYEE_DEPARTMENT D
WHERE D.Dnumber = E.Dno and E.Salary > 40000;

 3. 

SELECT COUNT(*)

FROM EMPLOYEE_REC

WHERE EMPLOYEE_REC.Dno NOT IN (SELECT EMPLOYEE_DEPARTMENT.Dnumber

FROM EMPLOYEE_DEPARTMENT

WHERE Zipcode =30332);

4.

SELECT City FROM EMP_CUSTOMERS

INTERSECT

SELECT City FROM EMP_SUPPLIERS
 

ORDER BY City;

LAB 20

1. 

2.

LAB 21