java数据库问题
我在jsp文件中用到了ResultSet,但是存在以下问题
1。用过rs后,执行rs.close()则出现错误:rs is closed
2。我不想让rs把完全相同的纪录合并,故在sql语句中加了关键字“all”,单ResultSet好像不支持all,相同纪录还是合并了
3。当while(i<=answernum&&rs.next())中,i<=answernum是true,但rs.next())是false时,出现如下错误:rs is closed
源代码如下:
<%@page contentType="text/html;charset=gb2312" %>
<%@page import="java.io.*,java.sql.*,java.util.*" %>
<jsp:useBean id="check" scope="page" class="bbs.Check" />
<%
sql="select * from ever_user where UID in (select Author from answer where QuestionID="+num+")";
rs=check.executeQuery(sql);
int tempnum=0;
int i=1;
while(i<=answernum&&rs.next())
{
tempnum=rs.getInt("Num");
currentgrace=rs.getInt("ExpertGrace");
currentgrace=currentgrace+intgrace[i];
sql="update ever_user set ExpertGrace="+currentgrace+"whereNum="+tempnum;
check.executeUpdate(sql);
i++;
}
rs.close()//加上此句则出错
%>
本人乃java菜鸟,还望大家多指教!!谢谢!!!!!!!!!!