Single Row Returns More than 1 row

Question

I have this query that displays the HOME telephone number of an EMP, however I have to put that Select on the field, since that field is HOME phone.
The Outputs are:
Name
Address
Birthday
Home Phone
Mobile Phone
Salary
Manager
My input is:
ID
How am I going to query the HomePhone and CellPhone, those number are on 1 field called CONTACT_NO however there is an INDICATOR field that tell either its HOME, CELL, BUSS, FAX... etc..

Answer 1

What they have done is a correlated subquery and what you have done is a direct join both give different result.
Check this out.
SQL> select * from emp order by empno;
     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     DEPTNO
         1 SMITH      CLERK           7902 17-DEC-80        800                    20
         2 ALLEN      SALESMAN        7698 20-FEB-81       1600        300         30
         3 WARD       SALESMAN        7698 22-FEB-81       1250        500         30
         4 JONES      MANAGER         7839 02-APR-81       2975                    20
         5 MARTIN     SALESMAN        7698 28-SEP-81       1250       1400         30
         6 BLAKE      MANAGER         7839 01-MAY-81       2850                    30
         7 CLARK      MANAGER         7839 09-JUN-81       2450                    10
         8 SCOTT      ANALYST         7566 19-APR-87       3000                    20
         9 KING       PRESIDENT            17-NOV-81       5000                    10
        10 TURNER     SALESMAN        7698 08-SEP-81       1500          0         30
10 rows selected.
SQL> select * from phone order by empno;
     EMPNO PHONE_TYPE   PHONE_NO
         1 HOME       9999999999
         2 CELL       1111111111
         2 HOME       9999999999
         3 HOME       9999999999
         8 CELL       1111111111
         8 HOME       9999999999
        10 HOME       9999999999
7 rows selected.A direct join gives this output.
SQL> select e.empno, e.ename, p.phone_no
  2    from emp e, phone p
  3   where e.empno = p.empno
  4     and p.phone_type = 'HOME';
     EMPNO ENAME        PHONE_NO
         1 SMITH      9999999999
         2 ALLEN      9999999999
         3 WARD       9999999999
         8 SCOTT      9999999999
        10 TURNER     9999999999And a Correlated subquery gives this output.
SQL> select e.empno,e.ename,(select phone_no
  2                            from phone
  3                           where empno = e.empno
  4                             and phone_type = 'HOME') phone_no
  5    from emp e;
     EMPNO ENAME        PHONE_NO
         1 SMITH      9999999999
         2 ALLEN      9999999999
         3 WARD       9999999999
         4 JONES
         5 MARTIN
         6 BLAKE
         7 CLARK
         8 SCOTT      9999999999
         9 KING
        10 TURNER     9999999999
10 rows selected.But a simple outer join can give the result as above.
SQL> select e.empno, e.ename, p.phone_no
  2    from emp e, phone p
  3   where p.empno (+)= e.empno
  4     and p.phone_type (+) = 'HOME';
     EMPNO ENAME        PHONE_NO
         1 SMITH      9999999999
         2 ALLEN      9999999999
         3 WARD       9999999999
         8 SCOTT      9999999999
        10 TURNER     9999999999
         5 MARTIN
         6 BLAKE
         7 CLARK
         4 JONES
         9 KING
10 rows selected.Thanks,
Karthick.