View based on function, correct query treated as bad - oracle

Question

This is code:
CREATE TABLE emp_where (where_clause VARCHAR2(4000));
INSERT INTO emp_where (where_clause)
VALUES ('first_name=''KING'' or department_id = 20');
commit;
CREATE OR REPLACE TYPE t_emp_rec AS OBJECT (
EMPLOYEE_ID NUMBER(4),
FIRST_NAME VARCHAR2(10),
JOB_ID VARCHAR2(9),
MANAGER_ID NUMBER(4),
HIRE_DATE DATE,
SALARY NUMBER(7,2),
DEPARTMENT_ID NUMBER(2)
);
/
CREATE OR REPLACE TYPE t_emp_tab AS TABLE OF t_emp_rec;
/
CREATE OR REPLACE FUNCTION emp_fn RETURN t_emp_tab
PIPELINED IS
l_sql VARCHAR2(32767);
l_where VARCHAR2(4000);
TYPE l_cur_type IS REF CURSOR;
l_cur l_cur_type;
l_rec employees%ROWTYPE;
BEGIN
SELECT where_clause INTO l_where FROM emp_where;
l_sql := 'SELECT * FROM employees WHERE ' || l_where;
OPEN l_cur FOR l_sql;
LOOP
FETCH l_cur
INTO l_rec;
EXIT WHEN l_cur%NOTFOUND;
PIPE ROW(t_emp_rec(EMPLOYEE_ID => l_rec.EMPLOYEE_ID
,FIRST_NAME => l_rec.FIRST_NAME
,JOB_ID => l_rec.JOB_ID
,MANAGER_ID => l_rec.MANAGER_ID
,hire_date => l_rec.hire_date
,SALARY => l_rec.SALARY
,DEPARTMENT_ID => l_rec.DEPARTMENT_ID));
END LOOP;
RETURN;
EXCEPTION
WHEN OTHERS THEN
raise_application_error(-20000, SQLERRM || chr(10) || l_sql);
END;
/
CREATE OR REPLACE VIEW emp_vw AS
UPDATE emp_where SET where_clause = 'EMPLOYEE_ID BETWEEN 100 and 200';
COMMIT;
SELECT * FROM emp_vw;
When I execute SELECT * FROM emp_vw; with this clause: EMPLOYEE_ID BETWEEN 100 and 200
Oracle gives me an error
ORA-20000: ORA-06502: PL/SQL: numeric or value error: number precision too large
SELECT * FROM employees WHERE EMPLOYEE_ID BETWEEN 100 and 200
But when I execute query itself (SELECT * FROM employees WHERE EMPLOYEE_ID BETWEEN 100 and 200) there is no error. Another scenario -
when clause is 'deparment_id = 20', executing a view is correct. But when I change '=' to '>' (department_id > 20) - numeric or value error: number precision too large.
Can someone explain me how this is happening?

Answer 1

If I run:
DESCRIBE employees
Then I get the output:
Name Null Type
-------------- -------- ------------
EMPLOYEE_ID NOT NULL NUMBER(6)
FIRST_NAME VARCHAR2(20)
LAST_NAME NOT NULL VARCHAR2(25)
EMAIL NOT NULL VARCHAR2(25)
PHONE_NUMBER VARCHAR2(20)
HIRE_DATE NOT NULL DATE
JOB_ID NOT NULL VARCHAR2(10)
SALARY NUMBER(8,2)
COMMISSION_PCT NUMBER(2,2)
MANAGER_ID NUMBER(6)
DEPARTMENT_ID NUMBER(4)
If you compare it to your t_emp_rec object then you will see that most of the object attributes are a smaller size than the table columns.
Change the object to have the same sizes and it should work:
CREATE OR REPLACE TYPE t_emp_rec AS OBJECT (
EMPLOYEE_ID NUMBER(6),
FIRST_NAME VARCHAR2(20),
JOB_ID VARCHAR2(10),
MANAGER_ID NUMBER(6),
HIRE_DATE DATE,
SALARY NUMBER(8,2),
DEPARTMENT_ID NUMBER(4)
);
/