Select query on emp table

Question

Hi,
How to find display the o/p like manager name under dependent employess same like parent child relation ship on noraml emp table:
sample o/p:
name job
xx manger
yy sales
yy1 sales
aa manager
rr marketing
rr1 marketing
Thanks

Answer 1

921306 wrote:
so like this i need parent child relationship between the manager under employees....So join the parent entity with the child entity to create the parent-child relationship.
As both entities are in the same table, this means joining the table to itself. E.g.
SQL> select
  2          child.ename                     as CHILD,
  3          child.job                       as CHILD_JOB,
  4          nvl(parent.ename,'<none>')      as PARENT,
  5          parent.job                      as PARENT_JOB
  6  from emp parent,
  7       emp child
  8  where child.mgr = parent.empno (+)
  9  /
CHILD      CHILD_JOB PARENT     PARENT_JO
FORD       ANALYST   JONES      MANAGER
SCOTT      ANALYST   JONES      MANAGER
JAMES      CLERK     BLAKE      MANAGER
TURNER     SALESMAN  BLAKE      MANAGER
MARTIN     SALESMAN  BLAKE      MANAGER
WARD       SALESMAN  BLAKE      MANAGER
ALLEN      SALESMAN  BLAKE      MANAGER
MILLER     CLERK     CLARK      MANAGER
ADAMS      CLERK     SCOTT      ANALYST
CLARK      MANAGER   KING       PRESIDENT
BLAKE      MANAGER   KING       PRESIDENT
JONES      MANAGER   KING       PRESIDENT
SMITH      CLERK     FORD       ANALYST
KING       PRESIDENT <none>
14 rows selected.
SQL> The basic concept is easy - define the parent entity, define the child entity, join the parent to the child.
If some entities will not have parents (root entities), then an outer join is needed from the child entity to the parent entity.
Simply because both entities are in the same table, does not change the logic or approach. It is perfectly valid to self-join a table.