！ ResultSet一直获取不到值

public class studentjiemian {    public studentjiemian(String ch){        try{Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");            String url="jdbc:odbc:sour";            Connection con=DriverManager.getConnection(url);            Statement stmt=con.createStatement();                        beijing jFrame = new beijing();            jFrame.setVisible(true);            Dimension dimension = Toolkit.getDefaultToolkit().getScreenSize();            jFrame.setBounds(((int)dimension.getWidth() - 200) / 2, ((int)dimension.getHeight() - 300) / 2, 900, 675);            jFrame.setResizable(false);            jFrame.setLayout(null);            jFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);                    JLabel label = new JLabel();            label.setBounds(150,20,700,600);                        JLabel huanying=new JLabel("欢迎你来到学生奖学金管理系统");            huanying.setBounds(50,50,200,30);            label.add(huanying);                        String sqlstr="select username,usercollege,userprofessional from userinf where userid='ch' ";//这个ch是通过另一个类传过来的String值，输出也有值            ResultSet rs=stmt.executeQuery(sqlstr);//rs。next为false。行数也是0            if(rs.next()){                JLabel xingming=new JLabel(rs.getString("username"));                xingming.setBounds(50,100,100,30);                label.add(xingming);                                JLabel college=new JLabel(rs.getString("usercollege"));                college.setBounds(50,150,100,30);                label.add(college);                                JLabel professional=new JLabel(rs.getString("userprofessional"));                professional.setBounds(50,200,100,30);                label.add(professional);            }                jFrame.add(label);