Single sql query-please help

Question

Hi experts,
what i want to do is write a single query which will show whether a employee
exits in the company or not.I have two tables emp and dept.There are as follows.
SQL> select * from emp;
NAME DEPTNO EMPNO
xxx 10 33036
YYY 12 2345
ZZZ 13 678
KKK 14 5678
RRR 15 7865
SQL> select * from dept;
DEPTNO LOCATION
10 AAA
11 BBB
12 CCC
13 DDD
what i want is it will select records from the emp table and find whether corrosponding
deptno really exists in the dept table.If the value is found in deptno column the dept table then it will set the value
Y other wise it will be N and all i have to do with the help of a single query.
expected result
name empno exists
xxx 33036 Y
YYY 2345 Y
ZZZ 678 Y
KKK 5678 N
RRR 7865 N
Please help.
Regards
Rajat

Answer 1

SELECT EMPNO, NAME , EMPNO , NVL( ( SELECT 'Y' FROM    DEPT WHERE EMP.DEPTNO=DEPT.DEPTNO),'N') EXIST
FROM EMP
ORDER BY 1
Demo
SQL> WITH EMP AS(
  2  SELECT 'XXX' NAME , 10 DEPTNO ,33036  EMPNO FROM DUAL UNION
  3  SELECT 'YYY', 12, 2345 FROM DUAL UNION
  4  SELECT 'ZZZ', 13 ,678 FROM DUAL UNION
  5  SELECT 'KKK', 14 ,5678 FROM DUAL UNION
  6  SELECT 'RRR', 15 ,7865 FROM DUAL  ),
  7  DEPT AS(
  8  SELECT 10  DEPTNO,'AAA' DNAME FROM DUAL UNION
  9  SELECT 11 ,'BBB' FROM DUAL UNION
10  SELECT 12 ,'CCC' FROM DUAL UNION
11  SELECT 13 ,'DDD'FROM DUAL )
12  SELECT EMPNO, NAME , EMPNO , NVL( ( SELECT 'Y' FROM    DEPT WHERE EMP.DEPTNO=DEPT.DEPTNO),'N')
EXIST
13  FROM EMP
14  ORDER BY 1
15  /
     EMPNO NAM      EMPNO E
       678 ZZZ        678 Y
      2345 YYY       2345 Y
      5678 KKK       5678 N
      7865 RRR       7865 N
     33036 XXX      33036 Y
SQL> Edited by: Salim Chelabi on Dec 7, 2008 4:15 AM