Simple way to invalidate SqlDataSource cache programmatically

EnableCaching and CacheDuration are the normal cache-related properties of the data source controls, but they don't give you the convenience to invalidate the cache on-demand. Some people use the SqlCacheDependency, where ASP.NET worker process will poll for changes in the SqlCacheTablesForChangeNotification when a change in monitored table triggers the "notification". This measure is somewhat clumsy in that:

1. You have to use aspnet_regsql command line to enable notifications for the database;
2. ASP.NET uses a polling mechanism, and you have to both write code and alter your web.config

There is a simpler way though: use CacheKeyDependency, where you make the data source cache dependent on another item in the data cache (CacheKeyDependency). Details follow:

• Add CacheKeyDependency in aspx:

<asp:SqlDataSource ID="x" EnableCaching="True" CacheKeyDependency="MyCacheDependency" />

• Add some code in aspx.cs:

protected void Page_Load(object sender, EventArgs e)
{ // Or somewhere else before the DataBind() takes place
  if (!IsPostBack)
  {
      ...
      if (Cache["MyCacheDependency"] == null)
      {
        Cache["MyCacheDependency"] = DateTime.Now;
      }
  }
}

• Where you make changes to the database table and want to invalidate cache so that next time a data binding will see the changes:

// Evict cache items with an update in dependent cache:
Cache["MyCacheDependency"] = DateTime.Now;

You can use any value instead of DateTime.Now as long as they are different to trigger the refresh.
Ref: 1. ASP.NET Caching: SQL Cache Dependency With SQL Server 2000
2. Accessing and Updating Data in ASP.NET 2.0: Declaratively Caching Data