IBM MainFrame Question:
select distinct(empid),distinct(dept),name
from EMP
will the above query work?
Answer:
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
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