private void btlogin_Click(object sender, EventArgs e){string username = null; string password = null ; if (tbusername、Text == ””) { MessageBox、Show("您没有输入用户名
","错误提示"); return; } if (tbmima、Text == "") { MessageBox、Show("您没有输入密码
","错误提示"); return; } DataSet dst = new DataSet();string connstr = ”Data Source=(local);Initial Catalog=Message;Integrated Security=True";SqlConnection con = new SqlConnection(connstr);con、Open();string str = "select * from 登录”;SqlDataAdapter sda = new SqlDataAdapter(str, con);SqlmandBuilder scd = new SqlmandBuilder(sda);sda、Fill(dst, "tong");dataGridView1、DataSource = dst、Tables[”tong”]、DefaultView;username = dataGridView1、Rows[0]、Cells[0]、Value、ToString()、Trim();password = dataGridView1、Rows[0]、Cells[1]、Value、ToString()、Trim();if (tbusername、Text、Equals(username)