The object represents a query notification dependency between an application and an instance of SQL Server 2005. An application can create a object and register to receive notifications via the OnChangeEventHandler event handler.
Assembly: System.Data (in System.Data.dll)
is ideal for caching scenarios, where your ASP.NET application or middle-tier service needs to keep certain information cached in memory. allows you to receive notifications when the original data in the database changes so that the cache can be refreshed.
To set up a dependency, you need to associate a object to one or more SqlCommand objects. To receive notifications, you need to subscribe to the OnChange event. For more information about the requirements for creating queries for notifications, see "Creating a Query for Notification" in SQL Server Books Online.
was designed to be used in ASP.NET or middle-tier services where there is a relatively small number of servers having dependencies active against the database. It was not designed for use in client applications, where hundreds or thousands of client computers would have objects set up for a single database server. If you are developing an application where you need reliable sub-second notifications when data changes, review the sections Planning an Efficient Query Notifications Strategy and Alternatives to Query Notifications in the Planning for Notifications topic in SQL Server Books Online.
requires the .NET Framework version 2.0 and SQL Server 2005. For more information, see Query Notifications in SQL Server (ADO.NET) and "Building Notification Solutions" in SQL Server Books Online.
The OnChange event may be generated on a different thread from the thread that initiated command execution.
Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.