Solve the Query plz

Question

I am having employee table like
empId ename mgrid (empid id primary key,MgrId is foreign key ref of empId)
1 a null
2 b 1
3 c 1
4 d 2
5 e 2
6 f 3
i need the out put like
empId ename mgrid level
1 a null 1
2 b 1 2
3 c 1 2
4 d 2 3
5 e 2 3
6 f 3 3

Answer 1

SELECT    empId, ename, mgrid ,level
      FROM employees
START WITH mgrid IS NULL
CONNECT BY prior empId = mgrid;
SQL> SELECT     empno, ename, mgr, LEVEL
  2        FROM emp_test
  3  START WITH mgr IS NULL
  4  CONNECT BY prior empno = mgr;
     EMPNO ENAME             MGR      LEVEL
      7839 KING                           1
      7566 JONES            7839          2
      7788 SCOTT            7566          3
      7902 FORD             7566          3
      7698 BLAKE            7839          2
      7699 DAVID            7839          2
      7782 CLARK            7839          2
7 ligne(s) sélectionnée(s).
SQL> select * from emp_test;
     EMPNO ENAME      JOB              MGR HIREDATE          SAL       COMM     DEPTNO
      7698 BLAKE      MANAGER         7839 1981-05-01      20000                    30
      7566 JONES      MANAGER         7839 1981-04-02       5950                    20
      7699 DAVID      MANAGER         7839 1981-05-01      20000                    30
      7782 CLARK      MANAGER         7839 1981-06-09      20000                    10
      7839 KING       PRESIDENT            1981-11-17      10000                    10
      7902 FORD       ANALYST         7566 1981-12-03       6000                    20
      7788 SCOTT      ANALYST         7566 2087-04-19       6000                    20
7 ligne(s) sélectionnée(s).
SQL>