IBM MainFrame Interview Question:

select distinct(empid),distinct(dept),name
from EMP
will the above query work?

Submitted by: Administrator

No, It will not work. SELECT DISTINCT works only for single
cloumn.

DISTINCT can be applied multiple times only when you want
to apply aggregate functions such as COUNT, AVG & SUM.
e.g.
SELECT COUNT(EMPNO)/COUNT(DISTINCT(WORKDEPT)), COUNT
(DISTINCT(JOB))
FROM DSN8810.EMP
Submitted by: Administrator