create a procedure with cursor as parameter - plsql

Question

I wrote this code and it works ok:
declare
cursor c_emp is
select last_name, first_name from employees;
type c_list is table of employees.last_name%type index by binary_integer;
type c_list2 is table of employees.first_name%type index by binary_integer;
last_list c_list;
first_list c_list2;
counter integer := 0;
begin
for i in c_emp loop
counter := counter + 1;
last_list(counter) := i.last_name;
first_list(counter) := i.first_name;
dbms_output.put_line('Employee(' || counter || '): ' || last_list(counter) || ' ' || first_list(counter));
end loop;
end;
/
This time I am trying to make procedure with parameters that I can insert the table name and column into the cursor. And I have tried with this :
create or replace procedure show_data(tab_name in varchar2, data_list in varchar2)
is
str varchar2(100);
str2 varchar2(100);
column_name varchar2(100);
begin
str := 'select ' || data_list || ' from ' || tab_name;
for vRec in str loop
dbms_output.put_line(str);
end loop;
end;
/
It gave a error which the str is not a cursor. I am not sure that if cursor can be done in this way, but from the error it seems it can't.
Which part of my code is wrong, or because I didn't declare my cursor? But if i declare my cursor, I can't get the parameter by using dynamic sql way.

Answer 1

The below should produce the same result as your original PL/SQL block. Note that the table_name can be dynamic and so can the data_list but you need to know the column names in the data_list to be able to fetch from the cursor and then print them.
create or replace procedure show_data(tab_name in varchar2
, data_list in varchar2)
is
str varchar2(100);
str2 varchar2(100);
column_name varchar2(100);
TYPE cursor_ref IS REF CURSOR;
vRec_cursor cursor_ref;
counter integer = 0;
last_name employee.last_name%TYPE;
first_name employee.first_name%TYPE;
begin
str := 'select ' || data_list || ' from ' || tab_name;
open vRec_cursor for str;
loop
FETCH vRec_cursor INTO last_name, first_name;
EXIT WHEN vRec_cursor%NOTFOUND;
dbms_output.put_line('Employee(' || counter || '): ' || last_name || ' ' || first_name;
counter = counter + 1;
end loop;
end;
/
NOTE: Haven't run the above code yet