Server Error in '/store2' Application.

Operator '=' is not defined for type 'DBNull' and type 'Integer'.

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: Operator '=' is not defined for type 'DBNull' and type 'Integer'.

Source Error:


Line 58: <b>ISBN: <%=r("Code")%></b><br />
Line 59: <% if r("IssueDate") isnot System.DbNull.Value then %>
Line 60: <%if r("ShopID")=1 then%>
Line 61: <b>Xuất bản: </b><%=Month(r("IssueDate")) & "/" & Year(r("IssueDate")) %> <br />
Line 62: 

Source File: D:\WebsiteMK\mk.net\store2\View.aspx    Line: 60

Stack Trace:


[InvalidCastException: Operator '=' is not defined for type 'DBNull' and type 'Integer'.]
   Microsoft.VisualBasic.CompilerServices.Operators.ConditionalCompareObjectEqual(Object Left, Object Right, Boolean TextCompare) +1260111
   ASP.index_aspx.__Render__control1(HtmlTextWriter __w, Control parameterContainer) in D:\WebsiteMK\mk.net\store2\View.aspx:60
   System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) +268
   System.Web.UI.Control.RenderChildren(HtmlTextWriter writer) +13
   System.Web.UI.Page.Render(HtmlTextWriter writer) +29
   System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) +66
   System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) +100
   System.Web.UI.Control.RenderControl(HtmlTextWriter writer) +25
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1303


Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.7.3062.0