3层架构c＃。

Question

我的3层架构存在问题。由于从对象到Int的隐式转换，我似乎无法计算玩家的数量。

的DropDownList

protected void ddlManufacturer_SelectedIndexChanged(object sender, EventArgs e)
{
    BLLPlayer playerBLL = new BLLPlayer();

 Label1.Text =  playerBLL.countPlayer(Convert.ToInt32(ddlManufacturer.SelectedValue)).ToString();
}

BLLPlayer

public int countPlayer (int ManufacturerID)
   {

   return Adapter.ScalarQuery(ManufacturerID);

   }

错误

Answer 1

如果ScalarQuery在引擎盖下返回int，那么：

return (int)Adapter.ScalarQuery(ManufacturerID);

但它可能会返回一个字符串，所以你需要

return Convert.ToInt32(Adapter.ScalarQuery(ManufacturerID));

Answer 2

试试这个：

  return (int)Adapter.ScalarQuery(ManufacturerID);

或者这个：

  public object countPlayer (int ManufacturerID)

Answer 3

请转换Adapter.ScalarQuery（ManufacturerID）;到int

Answer 4

return Convert.ToInt32(Adapter.ScalarQuery(ManufacturerID));

或

int playerCount=0;

var success=Int32.TryParse(Adapter.ScalarQuery(ManufacturerID), ref playerCount);

if(success)
return playerCount;
else
//handle when parsing failed