关于%ROWTYPE的使用方法，可以简便PL/SQL的写法，而且据说安全。
content:
declare
v_emp emp%rowtype;
cursor c_emp is select * from emp;
begin
open c_emp;
loop
fetch c_emp into v_emp;
exit when c_emp%NOTFOUND;
dbms_output.put_line('Salary of Employee 'v_emp.ename' is 'v_emp.sal);
end loop;
close c_emp;
end;
