How to get value from nested table in pl sql table - plsql

Question

I have created nested table as follow:
CREATE OR REPLACE TYPE EMP_NO_NAME
AS OBJECT
(
EMPNO NUMBER(4),
ENAME VARCHAR2(20),
JOB VARCHAR2(20),
MGR NUMBER(5),
HIREDATE DATE,
SAL NUMBER(7,2)
);
CREATE OR REPLACE TYPE EMP_TABLE IS TABLE OF EMP_NO_NAME;
-----------------------
CREATE TABLE NESTED_EMP
(
DEPTNO NUMBER(2) ,
EMPLOYEE EMP_TABLE
)
NESTED TABLE EMPLOYEE STORE AS NESTED_EMPLOYEE;
INSERT INTO NESTED_EMP (DEPTNO,EMPLOYEE)
VALUES (10,EMP_TABLE(EMP_NO_NAME(7839,'KING','PRESIDENT',NULL,'17-NOV-81',5000),
EMP_NO_NAME(7782,'CLARK','MANAGER',7839,'09-JUN-81',2450),
EMP_NO_NAME(7934,'MILLER','CLERK',7782,'23-JAN-82',1300)
)
);
INSERT INTO NESTED_EMP (DEPTNO,EMPLOYEE)
VALUES (20,EMP_TABLE(EMP_NO_NAME(7566,'JONES','MANAGER',7839,'02-APR-81',2975),
EMP_NO_NAME(7902,'FORD','ANALYST',7566,'03-DEC-81',3000),
EMP_NO_NAME(7369,'SMITH','CLERK',7902,'17-DEC-80',800),
EMP_NO_NAME(7788,'SCOTT','ANALYST',7566,'09-DEC-82',3000),
EMP_NO_NAME(7876,'ADAMS','CLERK',7788,'12-JAN-83',1100)
)
);
INSERT INTO NESTED_EMP (DEPTNO,EMPLOYEE)
VALUES (20,EMP_TABLE(EMP_NO_NAME(7698,'BLAKE','MANAGER',7839,'01-MAY-81',2850),
EMP_NO_NAME(7654,'MARTIN','SALESMAN',7698,'28-SEP-81',1250),
EMP_NO_NAME(7499,'ALLEN','SALESMAN',7698,'20-FEB-81',1600),
EMP_NO_NAME(7844,'TURNER','SALESMAN',7698,'08-SEP-81',1500),
EMP_NO_NAME(7900,'JAMES','CLERK',7698,'03-DEC-81',950),
EMP_NO_NAME(7521,'WARD','SALESMAN',7698,'22-FEB-81',1250)
)
);
Now I getting the value of nested table in plsql:
DECLARE
CURSOR EMPLOYEE IS
select p.* from NESTED_EMP p1 ,table(p1.employee) p;
V_EMP EMP_TABLE;
BEGIN
FOR V_EMP IN EMPLOYEE
LOOP
EXIT WHEN EMPLOYEE%NOTFOUND;
END LOOP;
FOR MYINDEX IN V_EMP.FIRST..V_EMP.LAST
LOOP
DBMS_OUTPUT.PUT_LINE(V_EMP(MYINDEX).ENAME);
END LOOP;
END;
/
END;
Error report:
ORA-06531: Reference to uninitialized collection ORA-06512: at line 10
06531. 00000 - "Reference to uninitialized collection"
*Cause: An element or member function of a nested table or varray
was referenced (where an initialized collection is needed)
without the collection having been initialized.
*Action: Initialize the collection with an appropriate constructor
or whole-object assignment.
How to get nested table value in plsql table ?

Answer 1

The problem with your code is that V_EMP is not actually of type EMP_TABLE. Rather, it's an EMPLOYEE.ROWTYPE. When you initialize a cursor for loop, the variable is automatically made an appropriate ROWTYPE, overriding any previous declarations.
The good news is that, since you've already referenced the nested table in the query, you don't need to do so in the loop (it's already been exploded). Your PL/SQL can be vastly simplified:
DECLARE
CURSOR employee IS
SELECT p.*
FROM nested_emp p1 CROSS JOIN TABLE (p1.employee) p;
BEGIN
FOR v_emp IN employee LOOP
DBMS_OUTPUT.put_line (v_emp.ename);
END LOOP;
END;
/
You'll notice the EXIT WHEN was removed as well. A cursor for loop terminates automatically after the last record.
An alternative would be to not explode the nested table in the query. Then you would need two loops:
DECLARE
CURSOR employee IS
SELECT p.*
FROM nested_emp p;
BEGIN
FOR v_emp IN employee LOOP
for i in v_emp.employee.first..v_emp.employee.last loop
DBMS_OUTPUT.put_line (v_emp.employee(i).ename);
end loop;
END LOOP;
END;
/