SqlConnection conn = new SqlConnection("server =127.0.0.1;uid = sa; pwd =allen;database =MaterialDataBase");
            string cmd = "select * from Users where UserName='textBox1.Text' and Password='textBox2.Text'";
            SqlCommand command = new SqlCommand(cmd,conn);
            conn.Open();
            SqlDataReader read = command.ExecuteReader();
            if (read.Read())
            { 
                MessageBox.Show("登陆");
                this.DialogResult = DialogResult.OK;
            
            }
            else
            {
                MessageBox.Show("登陆失败"); 
                this.DialogResult = DialogResult.Cancel; 
            }