The System.Web.Caching.SqlCacheDependency method returns an identifier used to uniquely track System.Web.Caching.SqlCacheDependency objects associated with an item or application. The unique identifier generated when using table-based notifications is partially dependent on the change identifier generated by the database.

When using SQL Server 2005-based query notifications, the unique identifier is null because sqprsqlong does not support returning unique identifiers for individual query notifications.