今天做图书管理系统，想要实现管理用和用户登录界面不同，怎么都不会，我是一个程序白痴，在数据库中把管理员设置为1，普通用户设置为2，C#中有个下拉列表，怎么通过选择下拉列表，实现管理员和普通用户登录不同，求大神指教。

           string UserID = this.username.Text.Trim();
            string UserPwd = this.password.Text.Trim();

            SqlConnection conn = new SqlConnection();
            conn.ConnectionString = "initial Catalog=booksys;Data source=DELL4-330338\\SQLEXPRESS;integrated Security=SSPI";
            conn.Open();          
            SqlCommand cmd = new SqlCommand();
            cmd.Connection = conn;
             = CommandType.Text;
            "select * from userinfo where UName='"+UserID+"' and UPwd='"+UserPwd+"'";
            SqlDataReader dr;
            dr =cmd.ExecuteReader();
             if 
                (dr.Read())
            {
                if (Form1.username.Equals(username) && user.Upwd.Equals(password))
                 {
                     if (comboBox1. == 1)
                     {
                         MessageBox.Show("欢迎管理员" + username + "登陆");
                     }
                     else
                     {
                         MessageBox.Show("欢迎用户" + username + "登陆");

                     }

                Form2 fm = new Form2();
                this.Hide();
                fm.Show();
                
            }
            else{
                this.lbError.Visible=true;
                this.lbError.Text="你输入的用户名或者密码错误，请重新输入！";
            }

           string UserID = this.username.Text.Trim();
            string UserPwd = this.password.Text.Trim();

            SqlConnection conn = new SqlConnection();
            conn.ConnectionString = "initial Catalog=booksys;Data source=DELL4-330338\\SQLEXPRESS;integrated Security=SSPI";
            conn.Open();          
            SqlCommand cmd = new SqlCommand();
            cmd.Connection = conn;
             = CommandType.Text;
            "select * from userinfo where UName='"+UserID+"' and UPwd='"+UserPwd+"'";
            SqlDataReader dr;
            dr =cmd.ExecuteReader();
             if 
                (dr.Read())
            {
                if (Form1.username.Equals(username) && user.Upwd.Equals(password))
                 {
                     if (comboBox1. == 1)
                     {
                         MessageBox.Show("欢迎管理员" + username + "登陆");
                     }
                     else
                     {
                         MessageBox.Show("欢迎用户" + username + "登陆");

                     }

                Form2 fm = new Form2();
                this.Hide();
                fm.Show();
                
            }
            else{
                this.lbError.Visible=true;
                this.lbError.Text="你输入的用户名或者密码错误，请重新输入！";
            }

就是发的错误代码。嫌麻烦，就弄了一个tabControl