select employee_id from employee table where department in 
('a1','a2','b1','b2');

Select emp_id from employee where dept IN (select all       
dept from employee);

Select emp_id from employee where dept IN (select DISTINCT 
dept from employee);

Select emp_id
from
employee
group by emp_id,dept
having count(*)>1;

hi all i hope this answer will help you


                emp
eid        ename        dep
001        manikandan   mainframe
002        karthi       java
003        jarin        mainframe
001        manikandan   java
003        jarin        testing
004        hariharan    java
001        manikandan   testing

select eid from emp e1 where 1 <
               
          (select count(*) from emp e2 where e1.eid=e2.eid)

let me know if any new answer

select employee-id
 from  table-name
 grtoup by employee-id
 having count(*) > 1

ans 5 need to be corrected...

subquery will fetch correct result but main query hw it 
will compare... ???

it supposed to be where eid exists(select eid...where 
e1.eid= e2.eid)

Another classic example of people replying to the queries 
in hurry..the answer #1, #2, #3, #4 & #7 are WRONG ANSWERS. 
Answer #6 is correct. Answer #5 also seems to be correct to 
me (unfortunatley I can't run & verify it at the moment, 
someone please verify it & let everyone know). 

Ram.g, FYI..EXISTS clause just denotes whether query after 
EXISTS clause returned any row or not, it NEVER give a 
count of the number of rows returned. Here need to find if 
there are more than one rows (i.e count is needed) so 
EXISTS can't be used here.

Ans 5 is also correct but it seems a bit compliceted