oracle function and cursor using dynamic table name - oracle11g

Question

IN my oracle database i want to create a function or procedure with cursor which will use dynamic table name.here is my code.
CREATE OR REPLACE Function Findposition ( model_in IN varchar2,model_id IN number) RETURN number IS cnumber number;
TYPE c1 IS REF CURSOR;
c2 c1;
BEGIN
open c2 FOR 'SELECT id,ROW_NUMBER() OVER ( ORDER BY id) AS rownumber FROM '||model_in;
FOR employee_rec in c2
LOOP
IF employee_rec.id=model_id then
cnumber :=employee_rec.rownumber;
end if;
END LOOP;
close c2;
RETURN cnumber;
END;
help me to solve this problem.IN

Answer 1

There is no need to declare a c1 type for a weakly typed ref cursor. You can just use the SYS_REFCURSOR type.
You can't mix implicit and explicit cursor calls like this. If you are going to OPEN a cursor, you have to FETCH from it in a loop and you have to CLOSE it. You can't OPEN and CLOSE it but then fetch from it in an implicit cursor loop.
You'll have to declare a variable (or variables) to fetch the data into. I declared a record type and an instance of that record but you could just as easily declare two local variables and FETCH into those variables.
ROWID is a reserved word so I used ROWPOS instead.
Putting that together, you can write something like
SQL> ed
Wrote file afiedt.buf
1 CREATE OR REPLACE Function Findposition (
2 model_in IN varchar2,
3 model_id IN number)
4 RETURN number
5 IS
6 cnumber number;
7 c2 sys_refcursor;
8 type result_rec is record (
9 id number,
10 rowpos number
11 );
12 l_result_rec result_rec;
13 BEGIN
14 open c2 FOR 'SELECT id,ROW_NUMBER() OVER ( ORDER BY id) AS rowpos FROM '||model_in;
15 loop
16 fetch c2 into l_result_rec;
17 exit when c2%notfound;
18 IF l_result_rec.id=model_id
19 then
20 cnumber :=l_result_rec.rowpos;
21 end if;
22 END LOOP;
23 close c2;
24 RETURN cnumber;
25* END;
SQL> /
Function created.
I believe this returns the result you expect
SQL> create table foo( id number );
Table created.
SQL> insert into foo
2 select level * 2
3 from dual
4 connect by level <= 10;
10 rows created.
SQL> select findposition( 'FOO', 8 )
2 from dual;
FINDPOSITION('FOO',8)
---------------------
4
Note that from an efficiency standpoint, you'd be much better off writing this as a single SQL statement rather than opening a cursor and fetching every row from the table every time. If you are determined to use a cursor, you'd want to exit the cursor when you've found the row you're interested in rather than continuing to fetch every row from the table.
From a code clarity standpoint, many of your variable names and data types seem rather odd. Your parameter names seem poorly chosen-- I would not expect model_in to be the name of the input table, for example. Declaring a cursor named c2 is also problematic since it is very non-descriptive.

Answer 2

You can do this, you don't need loop when you are using dynamic query
CREATE OR REPLACE Function Findposition(model_in IN varchar2,model_id IN number)
RETURN number IS
cnumber number;
TYPE c1 IS REF CURSOR;
c2 c1;
BEGIN
open c2 FOR 'SELECT rownumber
FROM (
SELECT id,ROW_NUMBER() OVER ( ORDER BY id) AS rownumber
FROM '||model_in || '
) WHERE id = ' || model_id;
FETCH c2 INTO cnumber;
close c2;
return cnumber;
END;