向Mysql中插入数据

public class LoginServlet extends HttpServlet {
public void doGet(HttpServletRequest req,HttpServletResponse resp)
throws ServletException,IOException{
process(req,resp);
}

protected void doPost(HttpServletRequest req,HttpServletResponse resp)
throws ServletException,IOException {
process(req,resp);
}

private void process(HttpServletRequest req,HttpServletResponse resp)
throws IOException{

try{
String username = req.getParameter("username");
String password=req.getParameter("password");

String sql="insert into bool(name,password) values("+username+","+password+")";
  String uri = "jdbc:mysql://localhost:3306/test";
   Connection conn = null;
   Statement stmt = null;
   ResultSet rs = null;
   try{
     Class.forName("com.jdbc.mysql.Driver");
   }catch(Exception e){
     System.out.println(e);
   } 

   try{
    conn = DriverManager.getConnection(uri,"root","wanglihui");
    stmt = conn.createStatement();
     stmt.executeQuery(sql);
        }catch(Exception e){
     System.out.println(e);
   }
   
   conn.close();

/////////////////JSP
  <form action = "./Login" method = "post">
    
    username:<input type="text" name="username"><br>
    password:<input type="password" name="password"><br>
    <input type="submit" value="submit">&nbsp;&nbsp;
    <input type ="reset" value="reset"><br>
    
    </form>
    

求指教 为什么在数据库中查询不到添加的内容呢？？