Need help to build SQl query

Question

Employee_table
Emp_no Emp_name Location
100          Ram Mumbai
200 Shyam Delhi
300 Jadu Bangalore
400 Madhu Hyderabad
500 Sidhu Kolkata
Employee_Comm
Emp_no Comm_flag
100 COMM
300 NO COMM
500 COMM
Note - No entry for employee 200 and 400, meand commision independent
SQL - when input flag would be COMM the display employee records 100,500,200,400
when input flag would be NO COMM the display employee records 300,200,400
     when input flag would be NULL the display employee records 100,200,300,400,500

Answer 1

Ohh,
Thank Karthick! I have changed the SQL to meet the need
WITH EMPLOYEE_TABLE
AS
    SELECT 100 EMP_NO,'RAM' EMP_NAME,'MUMBAI' LOCATION FROM DUAL UNION ALL
    SELECT 200,'SHYAM','DELHI' FROM DUAL UNION ALL
    SELECT 300,'JADU','BANGALORE' FROM DUAL UNION ALL
    SELECT 400,'MADHU','HYDERABAD' FROM DUAL UNION ALL
    SELECT 500,'SIDHU','KOLKATA' FROM DUAL
), EMPLOYEE_COMM
AS
    SELECT 100 EMP_NO,'COMM' COMM_FLAG FROM DUAL UNION ALL
    SELECT 300,'NO COMM' FROM DUAL UNION ALL
    SELECT 500,'COMM' FROM DUAL
SELECT  E1.EMP_NO, EMP_NAME, LOCATION, COMM_FLAG
FROM    EMPLOYEE_TABLE E1, EMPLOYEE_COMM E2
WHERE   E1.EMP_NO = E2.EMP_NO (+)
        AND (COMM_FLAG = :COMM_FLAG OR COMM_FLAG IS NULL);
Note: Derived from Karthick's SQL
*009*