プロジェクトのコードを作成しようとしていますが、無効な特定のキャスト エラーが引き続き発生します。困っているので誰か助けてください。前もって感謝します。
Server Error in '/c#project' Application.
Specified cast is not valid.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.InvalidCastException: Specified cast is not valid.
Source Error:
Line 39: cmd.Parameters.Add("@ProductId", OleDbType.Char).Value = strProductId;
Line 40: object oQty = cmd.ExecuteScalar();
Line 41: int intQuantityOnHand = (int)oQty;
Line 42: mDB.Close();
Line 43: int intBuyQuantity = int.Parse(ddlQty.Items[ddlQty.SelectedIndex].ToString());
Source File: c:\Users\jacob\Desktop\c#project\ProductDetails.aspx.cs Line: 41
Stack Trace:
[InvalidCastException: Specified cast is not valid.]
ProductDetails.btnBuy_Click(Object sender, EventArgs e) in c:\Users\jacob\Desktop\c#project\ProductDetails.aspx.cs:41
System.Web.UI.WebControls.Button.OnClick(EventArgs e) +118
System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +112
System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10
System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13
System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +36
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +5563
Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.272