<%@ Page Language="VB" Debug="True" %>
<%@ import Namespace="System.Data.SqlClient" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
Sub Page_Load(Src As Object, E As EventArgs)
' Declare the SqlCacheDependency instance, SqlDep.
Dim SqlDep As SqlCacheDependency
' Check the Cache for the SqlSource key.
' If it isn't there, create it with a dependency
' on a SQL Server table using the SqlCacheDependency class.
If Cache("SqlSource") Is Nothing
' Because of possible exceptions thrown when this
' code runs, use Try...Catch...Finally syntax.
Try
' Instantiate SqlDep using the SqlCacheDependency constructor.
SqlDep = New SqlCacheDependency("Northwind", "Categories")
' Handle the DatabaseNotEnabledForNotificationException with
' a call to the SqlCacheDependencyAdmin.EnableNotifications method.
Catch exDBDis As DatabaseNotEnabledForNotificationException
Try
SqlCacheDependencyAdmin.EnableNotifications("Northwind")
' If the database does not have permissions set for creating tables,
' the UnauthorizedAccessException is thrown. Handle it by redirecting
' to an error page.
Catch exPerm As UnauthorizedAccessException
Response.Redirect(".\ErrorPage.htm")
End Try
' Handle the TableNotEnabledForNotificationException with
' a call to the SqlCacheDependencyAdmin.EnableTableForNotifications method.
Catch exTabDis As TableNotEnabledForNotificationException
Try
SqlCacheDependencyAdmin.EnableTableForNotifications( _
"Northwind", "Categories")
' If a SqlException is thrown, redirect to an error page.
Catch exc As SqlException
Response.Redirect(".\ErrorPage.htm")
End Try
' If all the other code is successful, add MySource to the Cache
' with a dependency on SqlDep. If the Categories table changes,
' MySource will be removed from the Cache. Then generate a message
' that the data is newly created and added to the cache.
Finally
Cache.Insert("SqlSource", Source1, SqlDep)
CacheMsg.Text = "The data object was created explicitly."
End Try
Else
CacheMsg.Text = "The data was retrieved from the Cache."
End If
End Sub
</script>
<html >
<head runat="server">
<title>ASP.NET Example</title>
</head>
<body>
<form id="form1" runat="server">
<p>
</p>
<p>
<asp:SqlDataSource id="Source1" runat="server" SelectCommand="SELECT * FROM [Categories]" UpdateCommand="UPDATE [Categories] SET [CategoryName]=@CategoryName,[Description]=@Description,[Picture]=@Picture WHERE [CategoryID]=@CategoryID" ConnectionString="<%$ ConnectionStrings:Northwind %>"></asp:SqlDataSource>
<asp:GridView id="GridView1" runat="server" DataKeyNames="CategoryID" AllowSorting="True" AllowPaging="True" DataSourceID="Source1"></asp:GridView>
</p>
<p>
</p>
<p>
<asp:Label id="CacheMsg" runat="server" AssociatedControlID="GridView1"></asp:Label>
</p>
</form>
</body>
</html>