做JTREE遇到的问题~

Question

import java.sql.*;
import javax.swing.tree.*;
import java.util.Vector;
import java.util.*;public class MyTreeModel extends DefaultTreeModel {    private DefaultMutableTreeNode root;
    private DefaultMutableTreeNode parent;
    private Vector tables=new Vector();
    private Vector views=new Vector();
    private Vector systemTables=new Vector();
    public MyTreeModel(DefaultMutableTreeNode node){
       super(node);
       root=node;
       System.out.println(root);
       Connection conn=null;
       String[] types={"View","Table","System Table"};
       String[] title=new String[10000];
        try{
          Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
          conn=DriverManager.getConnection("jdbc:odbc:sql","sa","");
          DatabaseMetaData meta=conn.getMetaData();
          ResultSet rs=meta.getTables(null,null,"%",types);
          while(rs.next()){
            String type=rs.getString(4);
            String objName=rs.getString(3);
            if (type.toUpperCase().equals("TABLE")){
              tables.addElement(objName);
            }
            if (type.toUpperCase().equals("VIEW")){
              views.addElement(objName);
            }
            if (type.toUpperCase().equals("SYSTEM TABLE")){
              systemTables.addElement(objName);
            }
          }
          System.out.println(tables.size()+"Tables");
        }catch(Exception ex){
            System.out.println("An Error has Occured! Error Code: "+ex.getMessage());
        }    }
}我要从SQL数据库中读出各种表和视图并进行分类加到根结点，但我这段代码执行后，出现
An Error has Occured! Error Code: [Microsoft][ODBC SQL Server Driver]无效的描述符索引
这个错误信息，请问怎么解决呢~

Answer 1

String type=rs.getString(4);
String objName=rs.getString(3);总共有几列你知道吗？

Answer 2

ResultSet rs=meta.getTables(null,null,null,types);