string password = txtPassword.Text.ToString(); string name = txtUserName.SelectedItem.ToString(); string connecitonString = "server=(local);" + "intetrated security=SSPI;" + "database=App"; string mysql = "select 用户名 密码 from usertable"; SqlConnection myConnection = new SqlConnection(connecitonString); myConnection.Open(); SqlCommand cmd = new SqlCommand(mysql, myConnection); string Password = Convert.ToString(cmd.ExecuteScalar()); if (Password == password) { frmMain a = new frmMain(); a.ShowDialog(); } else { MessageBox.Show("密码输入错误!"); } myConnection.Close();