SqlDependency Class
 

The SqlDependency object represents a query notification dependency between an application and an instance of SQL Server. 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)

SystemObject
  System.Data.SqlClientSqlDependency

public sealed class SqlDependency
public ref class SqlDependency sealed 
[<Sealed>]
type SqlDependency = class end
Public NotInheritable Class SqlDependency
NameDescription
System_CAPS_pubmethod SqlDependency

Creates a new instance of the SqlDependency class with the default settings.

System_CAPS_pubmethod SqlDependency

Creates a new instance of the SqlDependency class and associates it with the SqlCommand parameter.

System_CAPS_pubmethod SqlDependency

Creates a new instance of the SqlDependency class, associates it with the SqlCommand parameter, and specifies notification options and a time-out value.

NameDescription
System_CAPS_pubproperty

Gets a value that indicates whether one of the result sets associated with the dependency has changed.

System_CAPS_pubproperty

Gets a value that uniquely identifies this instance of the SqlDependency class.

NameDescription
System_CAPS_pubmethod AddCommandDependency

Associates a SqlCommand object with this SqlDependency instance.

System_CAPS_pubmethod Equals

Determines whether the specified object is equal to the current object.(Inherited from Object.)

System_CAPS_pubmethod GetHashCode

Serves as the default hash function. (Inherited from Object.)

System_CAPS_pubmethod GetType

Gets the Type of the current instance.(Inherited from Object.)

System_CAPS_pubmethod System_CAPS_static Start

Starts the listener for receiving dependency change notifications from the instance of SQL Server specified by the connection string.

System_CAPS_pubmethod System_CAPS_static Start

Starts the listener for receiving dependency change notifications from the instance of SQL Server specified by the connection string using the specified SQL Server Service Broker queue.

System_CAPS_pubmethod System_CAPS_static Stop

Stops a listener for a connection specified in a previous Start call.

System_CAPS_pubmethod System_CAPS_static Stop

Stops a listener for a connection specified in a previous Start call.

System_CAPS_pubmethod ToString

Returns a string that represents the current object.(Inherited from Object.)

NameDescription
System_CAPS_pubevent OnChange

Occurs when a notification is received for any of the commands associated with this SqlDependency object.

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.

System_CAPS_noteNote

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. 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.

For more information, see Query Notifications in SQL Server and "Building Notification Solutions" in SQL Server Books Online.

System_CAPS_noteNote

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

Query notifications are supported only for SELECT statements that meet a list of specific requirements. The following table provides links to the Service Broker and Query Notifications documentation in SQL Server Books Online.

SQL Server Books Online

.NET Framework
Available since 2.0

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

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