java数据库登陆界面，在最下面的ActionPerformed中，数据库的语句是不是有错？

Question

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import java.util.*;
import java.sql.*;

public class Login extends Frame implements ActionListener
{
JLabel Labelusernumber=new JLabel("用户名：");
JLabel Labelpassword=new JLabel("密码：");
JLabel Labelshenfen=new JLabel("身份：");
JTextField TextFieldusernumber=new JTextField();
JPasswordField FieldPassword=new JPasswordField();
JButton button=new JButton("登录");
JComboBox JC=new JComboBox();

public Login()
{
    setTitle("超市销售信息管理系统");
    setLayout(null);
    Labelusernumber.setBounds(50,40,60,20);
    add(Labelusernumber);
    TextFieldusernumber.setBounds(100,40,80,20);
    add(TextFieldusernumber);
    Labelpassword.setBounds(50,80,60,20);
    add(Labelpassword);
    FieldPassword.setBounds(100,80,80,20);
    add(FieldPassword);
    Labelshenfen.setBounds(50,120,60,20);
    add(Labelshenfen);
    JC.setBounds(100,120,80,20);
    add(JC);
    JC.addItem(new String("老板"));
    JC.addItem(new String("雇员"));
    button.setBounds(50,160,60,20);
    add(button);
    button.addActionListener(this);
    setVisible(true);
    setBounds(0,0,230,200);
    addWindowListener(new WindowAdapter()
    {
        public void windowClosing(WindowEvent e)
    {
        System.exit(0);
    }
    });
}
public static void main(String args[])
{
    new Login();
}
public void actionPerformed(ActionEvent e)
{
    if(e.getSource()==button)
    {
        String unum=TextFieldusernumber.getText();
        String upassword=FieldPassword.getText();
        String box=(String)JC.getSelectedItem();
        String sql="select * from employee where Emnum='"+unum+"' and Emkey='"+upassword+"'";
        if(box.equals("老板"))
        {
            if((unum!=null&&(unum.equals("sada")))&&(upassword!=null&&(upassword.equals("0231"))))
            {
                        new ShowButton();

//new bossmanage();
}
}
else if(box.equals("雇员"))
{
try
{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
Connection con=DriverManager.getConnection("jdbc:odbc:DBInfo","user","123456");
Statement stm=con.createStatement();
ResultSet rs=stm.executeQuery(sql);
if(rs.next())
{
new ShowButton();
//new employeemanage();
}
}
catch(Exception ee)
{
}

        }
    }
}

}

Answer 1

Emkey是不是字符串还是数字，如果是数字，不要引号。