SqlDependency Class (System.Data.SqlClient)

SqlDependency Class

.NET Framework Class Library

SqlDependency Class

The SqlDependency object represents a query notification dependency between an application and an instance of SQL Server 2005. An application can create a SqlDependency object and register to receive notifications via the OnChangeEventHandler event handler.

Namespace: System.Data.SqlClient
Assembly: System.Data (in System.Data.dll)

Syntax

Visual Basic (Declaration)

Public NotInheritable Class SqlDependency

Visual Basic (Usage)

Dim instance As SqlDependency

public sealed class SqlDependency

Visual C++

public ref class SqlDependency sealed

JScript

public final class SqlDependency

Remarks

SqlDependency is ideal for caching scenarios, where your ASP.NET application or middle-tier service needs to keep certain information cached in memory. SqlDependency 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 SqlDependency 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.

Note:
SqlDependency 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 SqlDependency objects set up for a single database server.

SqlDependency 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.

Note:
The OnChange event may be generated on a different thread from the thread that initiated command execution.

Inheritance Hierarchy

System..::.Object
System.Data.SqlClient..::.SqlDependency

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Platforms

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.

Version Information

.NET Framework

Supported in: 3.5, 3.0, 2.0

Reference

SqlDependency Members

System.Data.SqlClient Namespace

Other Resources

Query Notifications in SQL Server (ADO.NET)