читай в доке, ключевое слово - NATIVE DYNAMIC SQL

CREATE OR REPLACE PROCEDURE query_invoice(
month VARCHAR2,
year VARCHAR2) IS
TYPE cur_typ IS REF CURSOR;
c cur_typ;
query_str VARCHAR2(200);
inv_num NUMBER;
inv_cust VARCHAR2(20);
inv_amt NUMBER;
BEGIN
query_str := 'SELECT num, cust, amt FROM inv_' || month ||'_'|| year
|| ' WHERE invnum = :id';
OPEN c FOR query_str USING inv_num;
LOOP
FETCH c INTO inv_num, inv_cust, inv_amt;
EXIT WHEN c%NOTFOUND;
-- process row here
END LOOP;
CLOSE c;
END;
/

Еще есть пакет DBMS_SQL