是这样的。我在百度云平台建了个数据库。然后服务器那块是用struct2写的。在登录模块那里有查询数据库操作.然后很成功.在注册模块就出了错.一路追查下去结果发现是插入sql语句未执行.然后继续尝试,update也不执行。于是默默发现除了查询，只要要写进去的sql语句都不执行。而且这玩意还不好google。求各位大神帮帮忙啊。在此谢过了
附上代码

                public class RegisterSQL {
    public List<User> registerList;
    public String  register(){
        String b=new String("") ;
        int i = 0;
        User user=registerList.get(0);
        ResultSet rs = null;
        MySql db=new MySql();
        Connection conn=db.connectMySQL();
        try {
            PreparedStatement ps=conn.prepareStatement("select * from user where username=?");
            ps.setString(1,user.getUsername());

            rs=ps.executeQuery();
            if (rs.next())
            {
                PreparedStatement ps1=conn.prepareStatement("insert into user(username,password,age,sex,phone) values (?,?,?,?,?)");
                ps1.setString(1,user.getUsername());
                ps1.setString(2,user.getPassword());
                ps1.setString(3,user.getAge());
                ps1.setString(4,user.getSex());
                ps1.setString(5,user.getPhone());
                i=ps1.executeUpdate();
                if (i>0)
                {
                    b="your register success";
                }
                else
                {
                    b="something wrong with the SQL,so please try again";
                }
            }
            else
            {
                System.out.println("test1");
                String sql = "insert into user(username,password,age,sex,phone)"+" values('"+user.getUsername()+"','"+user.getPassword()+"','"+user.getAge()+"','"+user.getSex()+"','"+user.getPhone()+"')";
                System.out.println("test2");
                db.excute(sql);
                b="ok";
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }       
        return b;
    }