Help with the query

Question

Hi
I need to execute a select statement base on an input parameter like the following. Please share your thoughts
select (case when param = 1 then
(select * from emp_1 a,dept_1 b
where a.dept_no=b.dept_no)
when param = 2 then
(select * from emp_2 a,dept_2 b
where a.dept_no=b.dept_no)
else
end)
from dual
Thanks

Answer 1

WITH emp_1 AS
     (SELECT 1 param, 2 dept_no
        FROM DUAL),
     dept_1 AS
     (SELECT 1 param, 2 dept_no
        FROM DUAL)
SELECT (CASE
           WHEN a.param = 0
              THEN (SELECT b.param
                      FROM emp_1 b
                     WHERE a.dept_no = b.dept_no)
                     ELSE 1
        END)
  FROM dept_1 a
try something like this