ResultSet：异常：set type是TYPE_FORWARD_ONLY - 为什么？ [英] ResultSet: Exception: set type is TYPE_FORWARD_ONLY -- why?

问题描述

我的代码非常简单：

pstat=con.prepareStatement("select typeid from users where username=? and password=?");             
pstat.setString(1, username);
pstat.setString(2, password);
rs=pstat.executeQuery();
int rowCount=0;
while(rs.next())
{       
    rowCount++;         
}
rs.beforeFirst();
if(rowCount>=1)
{
while(rs.next())
{
    typeID=rs.getInt(1);
}

但执行此代码时我得到了......

But when execute this code I am getting...

java.sql.SQLException: Result set type is TYPE_FORWARD_ONLY
at sun.jdbc.odbc.JdbcOdbcResultSet.beforeFirst(Unknown Source)
at server.ClientImpl.login(ClientImpl.java:57)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at sun.rmi.server.UnicastServerRef.dispatch(Unknown Source)
at sun.rmi.transport.Transport$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.Transport.serviceCall(Unknown Source)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(Unknown Source)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(Unknown Source)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)

是什么导致了这个以及如何我能解决吗？

What is causing this and how can I fix it?

推荐答案

将你的第一个陈述改为此

Change your first statement to this

pstat=con.prepareStatement("select typeid from users where username=? and password=?",
                            ResultSet.TYPE_SCROLL_SENSITIVE, 
                        ResultSet.CONCUR_UPDATABLE);

这样你可以前进和后退，所以不用担心

This way you can move forward and backward, so less things to worry about

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