Sample Paper – 2012
Class – XII
Subject – Informatics Practice

Q.1  Answer the following questions:

(a) Compare DDL and DML statements of SQL.

(b) Swati needs to remove all the rows from SALES table to release the storage space. But she does not want to remove the table structure. Which statement should she use?

(c) Meena uses a EMP table with following columns:
NAME ,SAL,ID,DNAME
She needs to display names of employees who have not been assigned any department or have been assigned “pathology” department. Pathology course’s names end with “Pathology”. She wrote the following query:
SELECT  NAME, SAL
FROM EMP, COURSE
WHERE DNAME = NULL OR DNAME = “%pathology”;
But the query is not producing result. Identify the problem.

(d) What is the importance of primary key in a table? Explain with example.