Dynamic SELECT Statement on Oracle 10G

DECLARE
n NUMBER;
sql_stmt VARCHAR2(255);
type DynaCur IS REF CURSOR;
c DynaCur;
BEGIN
select 'SELECT 1,b.* from (select rownum nrow,a.* from DBA_USERS a where
rownum=1) b' into sql_stmt from dual;
OPEN c FOR sql_stmt;
FETCH c into n;
dbms_output.put_line(n);
CLOSE c;
END;
/