案例：添加学生，然后返回该班级的所有学生。
create or replace procedure add_stu(
p_sid stu.sid%type,
p_sname stu.sname%type,
p_cid stu.cid%type,
p_data out sys_refcursor -- 输出变量,系统引用游标
)
as
begin
insert into stu(sid,sname,cid)
values(p_sid,p_sname,p_cid);
commit;
--将查询的结果集的地址放到引用游标变量中，再传递出去
open p_data for select * from stu where cid=p_cid;
end;
--PL/SQL 调用
declare
stu_data sys_refcursor;
stu_row stu%rowtype;
begin
add_stu(52,'b',1,stu_data);
fetch stu_data into stu_row;
while(stu_data%found)
loop
dbms_output.put_line(stu_row.sname);
fetch stu_data into stu_row;
end loop;
close stu_data;
end;
--java中调用
CallableStatement cstmt = null;
String spName = “{call add_stu(?,?,?,?)}";
cstmt = conn.prepareCall(spName);
cstmt.setInt(1, 工号);
…………
cstmt.registerOutParameter(4, Oracle.jdbc.OracleTypes.CURSOR); --设置第4个问号的值
cstmt.executeUpdate();
ResultSet rs = (ResultSet)cstmt.getObject(4);