private void button1_Click(object sender, EventArgs e)
 {
     if (txt_UserName.Text == "" || txt_Password.Text == "")
     {
         MessageBox.Show("Wpisz nazwę użytkownia i hasło");
         return;
     }
     try
     {
         //Create SqlConnection
         SqlConnection con = new SqlConnection(cs);
         SqlCommand    cmd = new SqlCommand("Select * from login where UserName=@username and Password=@password", con);
         cmd.Parameters.AddWithValue("@username", txt_UserName.Text);
         cmd.Parameters.AddWithValue("@password", txt_Password.Text);
         con.Open();
         SqlDataAdapter adapt = new SqlDataAdapter(cmd);
         DataSet        ds    = new DataSet();
         adapt.Fill(ds);
         con.Close();
         int count = ds.Tables[0].Rows.Count;
         if (count == 1)
         {
             MessageBox.Show("Logowanie się powiodło!");
             int     id   = Convert.ToInt32(ds.Tables[0].Rows[0]["id"]);
             Boolean mod  = Convert.ToBoolean(ds.Tables[0].Rows[0]["modpermission"]);
             String  name = Convert.ToString(ds.Tables[0].Rows[0]["username"]);
             User    user = new User(name, mod, id);
             this.Hide();
             if (!Convert.ToBoolean(ds.Tables[0].Rows[0]["modpermission"]))
             {
                 MainUserPage fm = new MainUserPage();
                 fm.user = user;
                 fm.Show();
             }
             if (Convert.ToBoolean(ds.Tables[0].Rows[0]["modpermission"]))
             {
                 ManagerPage fm = new ManagerPage();
                 fm.user = user;
                 fm.Show();
             }
         }
         else
         {
             MessageBox.Show("Logowanie nieudane!");
         }
     }
     catch (Exception ex)
     {
         MessageBox.Show(ex.Message);
     }
 }
        private void yesbtn_Click(object sender, EventArgs e)
        {
            using (SqlConnection con = new SqlConnection(cs))
            {
                con.Open();
                int        car_id = Convert.ToInt32(cartobuygrid.Rows[0].Cells["id"].Value);
                int        value  = Convert.ToInt32(cartobuygrid.Rows[0].Cells["price"].Value);
                DateTime   date   = DateTime.Today;
                SqlCommand cmd    = new SqlCommand("INSERT INTO [transaction] (client_id, car_id, date, value, accepted) VALUES (@client_id,  @car_id, @date, @value, 1)", con);
                cmd.Parameters.AddWithValue("@client_id", user.id);
                cmd.Parameters.AddWithValue("@car_id", car_id);
                cmd.Parameters.AddWithValue("@value", value);
                cmd.Parameters.AddWithValue("@date", date.ToString("d"));

                try
                {
                    cmd.ExecuteNonQuery();
                    MessageBox.Show("Zakup przebiegł pomyślnie!");
                }
                catch (Exception ex)
                {
                    MessageBox.Show("Zakup się nie powiódł!");
                    MessageBox.Show(ex.Message);
                }
                //SqlCommand cmds = new SqlCommand("DELETE FROM car WHERE id = CONVERT(int, @car_id)", con);
                SqlCommand cmds = new SqlCommand("UPDATE car SET available = 0 WHERE id = @car_id;", con);
                cmds.Parameters.AddWithValue("@car_id", car_id);
                try
                {
                    cmds.ExecuteNonQuery();
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.Message);
                }
                if (user.mod == true)
                {
                    ManagerPage menu = new ManagerPage();
                    menu.user = user;
                    menu.Show();
                    this.Close();
                }
                if (user.mod == false)
                {
                    MainUserPage menu = new MainUserPage();
                    menu.user = user;
                    menu.Show();
                    this.Close();
                }
            }
        }
 private void backtbn_Click(object sender, EventArgs e)
 {
     if (user.mod == true)
     {
         ManagerPage menu = new ManagerPage();
         menu.user = user;
         menu.Show();
         this.Close();
     }
     if (user.mod == false)
     {
         MainUserPage menu = new MainUserPage();
         menu.user = user;
         menu.Show();
         this.Close();
     }
 }
 private void backbtn_Click(object sender, EventArgs e)
 {
     clientgrid.CancelEdit();
     if (user.mod == true)
     {
         ManagerPage menu = new ManagerPage();
         menu.user = user;
         menu.Show();
         this.Close();
     }
     if (user.mod == false)
     {
         MainUserPage menu = new MainUserPage();
         menu.user = user;
         menu.Show();
         this.Close();
     }
 }