How to: Register Event Handlers and Subscribe to Event Handling in Visual Basic .NET
This section describes how to create an event handler and how to subscribe to a set of events in Microsoft Visual Basic .NET.
The code example shows how to set up the event handler and how to subscribe to the database events.
Setting up an event handler
Start Visual Studio 2005.
From the File menu, select New Project. The New Project dialog box appears.
In the Project Types pane, select Visual Basic. In the Templates pane, select Console Application.
(Optional) In the Name box, type the name of the new application.
Click OK to load the Visual Basic console application template.
On the Project menu, select Add Reference item. The Add Reference dialog box appears. Select Browse and locate the SMO assemblies in the C:\Program Files\Microsoft SQL Server\90\SDK\Assemblies folder. Select the following files:
Microsoft.SqlServer.ConnectionInfo.dll
Microsoft.SqlServer.Smo.dll
Microsoft.SqlServer.SqlEnum.dll
Microsoft.SqlServer.SmoEnum.dll
On the View menu, click Code.-Or-Select the Module1.vb window to display the code window.
In the code, before any declarations, type the following Imports statements to qualify the types in the SMO namespace:
Imports Microsoft.SqlServer.Management.Smo Imports Microsoft.SqlServer.Management.CommonInsert the code that follows this procedure into the main program.
Run and build the application.
Exemple
'Create an event handler subroutine that runs when a table is created.
Private Sub MyCreateEventHandler(ByVal sender As Object, ByVal e As ServerEventArgs)
Console.WriteLine("A table has just been added to the AdventureWorks database.")
End Sub
'Create an event handler subroutine that runs when a table is deleted.
Private Sub MyDropEventHandler(ByVal sender As Object, ByVal e As ServerEventArgs)
Console.WriteLine("A table has just been dropped from the AdventureWorks database.")
End Sub
Sub Main()
'Connect to the local, default instance of SQL Server.
Dim srv As Server
srv = New Server
'Reference the AdventureWorks database.
Dim db As Database
db = srv.Databases("AdventureWorks")
'Create a database event set that contains the CreateTable event only.
Dim databaseCreateEventSet As New DatabaseEventSet
databaseCreateEventSet.CreateTable = True
'Create a server event handler and set it to the first event handler subroutine.
Dim serverCreateEventHandler As ServerEventHandler
serverCreateEventHandler = New ServerEventHandler(AddressOf MyCreateEventHandler)
'Subscribe to the first server event handler when a CreateTable event occurs.
db.Events.SubscribeToEvents(databaseCreateEventSet, serverCreateEventHandler)
'Create a database event set that contains the DropTable event only.
Dim databaseDropEventSet As New DatabaseEventSet
databaseDropEventSet.DropTable = True
'Create a server event handler and set it to the second event handler subroutine.
Dim serverDropEventHandler As ServerEventHandler
serverDropEventHandler = New ServerEventHandler(AddressOf MyDropEventHandler)
'Subscribe to the second server event handler when a DropTable event occurs.
db.Events.SubscribeToEvents(databaseDropEventSet, serverDropEventHandler)
'Start event handling.
db.Events.StartEvents()
'Create a table on the database.
Dim tb As Table
tb = New Table(db, "Test_Table")
Dim mycol1 As Column
mycol1 = New Column(tb, "Name", DataType.NChar(50))
mycol1.Collation = "Latin1_General_CI_AS"
mycol1.Nullable = True
tb.Columns.Add(mycol1)
tb.Create()
'Remove the table.
tb.Drop()
'Wait until the events have occured.
Dim x As Integer
Dim y As Integer
For x = 1 To 1000000000
y = x * 2
Next
'Stop event handling.
db.Events.StopEvents()
End Sub