Cursor Variable in Nested Block

Question

Dear all,
I have a package that has procedures that open cursor variables and print the queries of sample schema HR. There's one procedure that opens the cursor with an input integer to choose which query that wants to be fetched. The other prints the query by fetching the cursor in a nested block with exceptions. The following package runs as intended, it prints all the three options without any problems:
CREATE OR REPLACE PACKAGE admin_data AS
TYPE gencurtyp IS REF CURSOR;
PROCEDURE open_cv (generic_cv IN OUT gencurtyp, choice INT);
procedure print_cv (generic_cv gencurtyp);
END admin_data;
CREATE OR REPLACE PACKAGE BODY admin_data AS
PROCEDURE open_cv (generic_cv IN OUT gencurtyp, choice INT) IS
BEGIN
IF choice = 1 THEN
OPEN generic_cv FOR SELECT * FROM jobs where job_id='ST_MAN';
ELSIF choice = 2 THEN
OPEN generic_cv FOR SELECT * FROM departments where department_id=270;
ELSIF choice = 3 THEN
OPEN generic_cv FOR SELECT * FROM employees where employee_id=206;
END IF;
END;
procedure print_cv (generic_cv gencurtyp)is
employees_rec employees%rowtype;
departments_rec departments%rowtype;
jobs_rec jobs%rowtype;
begin
fetch generic_cv into jobs_rec;
dbms_output.put_line(jobs_rec.job_title);
exception
when ROWTYPE_MISMATCH then
  begin
  fetch generic_cv into departments_rec;
  dbms_output.put_line(departments_rec.department_name);
  exception
  when ROWTYPE_MISMATCH then
    dbms_output.put_line('row mismatch');
    fetch generic_cv into employees_rec;
    dbms_output.put_line(employees_rec.first_name);
  when OTHERS then
    dbms_output.put_line('others');
    fetch generic_cv into employees_rec;
    dbms_output.put_line(employees_rec.first_name);
  end;
end print_cv;
END admin_data;
declare
some_cur admin_data.gencurtyp;
begin
admin_data.open_cv(some_cur,1);
admin_data.print_cv(some_cur);
admin_data.open_cv(some_cur,2);
admin_data.print_cv(some_cur);
admin_data.open_cv(some_cur,3);
admin_data.print_cv(some_cur);
admin_data.open_cv(some_cur,3);
admin_data.print_cv(some_cur);
admin_data.open_cv(some_cur,1);
admin_data.print_cv(some_cur);
admin_data.open_cv(some_cur,2);
admin_data.print_cv(some_cur);
end;
17  /
Stock Manager
Payroll
row mismatch
William
row mismatch
William
Stock Manager
Payroll
PL/SQL procedure successfully completed.The innermost block executes 'rowtype mismatch' exception block, which fetches
SELECT * FROM employees where employee_id=206 query.
This time, I switch the query fetch so that
SELECT * FROM employees where employee_id=206query is in the outermost block and
SELECT * FROM jobs where job_id='ST_MAN' is in the innermost block. The package body looks like this:
CREATE OR REPLACE PACKAGE BODY admin_data AS
PROCEDURE open_cv (generic_cv IN OUT gencurtyp, choice INT) IS
BEGIN
IF choice = 1 THEN
OPEN generic_cv FOR SELECT * FROM jobs where job_id='ST_MAN';
ELSIF choice = 2 THEN
OPEN generic_cv FOR SELECT * FROM departments where department_id=270;
ELSIF choice = 3 THEN
OPEN generic_cv FOR SELECT * FROM employees where employee_id=206;
END IF;
END;
procedure print_cv (generic_cv gencurtyp)is
employees_rec employees%rowtype;
departments_rec departments%rowtype;
jobs_rec jobs%rowtype;
begin
fetch generic_cv into employees_rec;
dbms_output.put_line(employees_rec.first_name);
exception
when ROWTYPE_MISMATCH then
  begin
  fetch generic_cv into departments_rec;
  dbms_output.put_line(departments_rec.department_name);
  exception
  when ROWTYPE_MISMATCH then
    dbms_output.put_line('row mismatch');
    fetch generic_cv into jobs_rec;
    dbms_output.put_line(jobs_rec.job_title);
  when OTHERS then
    dbms_output.put_line('others');
    fetch generic_cv into jobs_rec;
    dbms_output.put_line(jobs_rec.job_title);
  end;
end print_cv;
END admin_data;
then I run the same anonymous block, I get:declare
some_cur admin_data.gencurtyp;
begin
admin_data.open_cv(some_cur,1);
admin_data.print_cv(some_cur);
admin_data.open_cv(some_cur,2);
admin_data.print_cv(some_cur);
admin_data.open_cv(some_cur,3);
admin_data.print_cv(some_cur);
admin_data.open_cv(some_cur,3);
admin_data.print_cv(some_cur);
admin_data.open_cv(some_cur,1);
admin_data.print_cv(some_cur);
admin_data.open_cv(some_cur,2);
admin_data.print_cv(some_cur);
end;
17 /
others
Payroll
William
William
others
Payroll
PL/SQL procedure successfully completed.
The strangest thing is the innermost block execute OTHERS exception block instead of ROWTYPE MISMATCH and the the record doesn't fetch anything. What happen? How come the result is different when I only switch the query?
Best regards,
Val

Answer 1

Hi Sy,
thanks for the reply, yes I agree that the code is cumbersome, I'm studying to prepare OCP PL/SQL certification, so I'm playing around with cursor variable in order to grasp the whole concept. I'm observing the behaviour of weak cursor variable when getting passed into a function and fetched couple of times and exploring exception propagation in the same time. This why the code looks not relevant in the real world.
Anyway, I just curious how it behaves like that. Here's my instance info:
SQL> select * from v$version
  2  ;
BANNER
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
PL/SQL Release 11.2.0.1.0 - Production
CORE     11.2.0.1.0     Production
TNS for Linux: Version 11.2.0.1.0 - Production
NLSRTL Version 11.2.0.1.0 - Production