Connecting department code with employee table

Question

hi all,
i am using db10g.
i have
EMPLOYEE_MASTER
EMP_CODE
EMP_NAME
EMP_DEPT
primary key EMP_CODE and foreign key EMP_DEPT references DEPARTMENT_MASTER (primary key) DPT_CODE
DEPARTMENT_MASTER
DPT_CODE
DPT_NAME
DPT_LOCnow my question is first i have to get deparmtne name and corresponding employees.
dept A
x
y
z
dept b
a
b
c
etc..
somthing like connect by clause which i am not that much aware of?
i have written the below
SELECT 1, LEVEL, EMP_NAME, NULL, TO_CHAR(EMP_CODE)
FROM DEPARTMENT_MASTER,EMPLOYEE_MASTER
WHERE DPT_CODE = EMP_DEPT
CONNECT BY PRIOR EMP_DEPT = DPT_CODE
but i am getting
ERROR:
ORA-01436: CONNECT BY loop in user data
no rows selected Thanks..
Edited by: GD on Mar 12, 2012 1:20 AM

Answer 1

Something like this.
-- sample table
create table department
  deptno integer primary key,
  dname varchar2(100)
create table employee
  empno integer primary key,
  deptno integer,
  ename varchar2(100),
  sal  number(10,2),
  doj date,
  constraint employee_fk foreign key(deptno) references department(deptno)
-- sample data
insert into department(deptno, dname) values (1, 'IT Development');
insert into department(deptno, dname) values (2, 'IT Testing');
insert into employee(empno, ename, deptno, sal, doj) values(1, 'Karthick', 1, 100, sysdate-100);
insert into employee(empno, ename, deptno, sal, doj) values(2, 'Karthick_1', 1, 90, sysdate-110);
insert into employee(empno, ename, deptno, sal, doj) values(3, 'Ram', 2, 100, sysdate-100);
insert into employee(empno, ename, deptno, sal, doj) values(4, 'Ram_1', 2, 90, sysdate-110);
-- query to get employee name as a string for each department.
select dname, ltrim(sys_connect_by_path(ename, ','), ',') ename
  from (
          select d.dname, e.ename, row_number() over(partition by d.deptno order by e.empno) rno
            from employee e
            join department d
              on e.deptno = d.deptno
where connect_by_isleaf = 1      
start with rno = 1
connect by dname = prior dname
   and rno = prior rno + 1
/