How to: Register Event Handlers and Subscribe to Event Handling in Visual Basic .NET

[This topic is pre-release documentation and is subject to change in future releases. Blank topics are included as placeholders.]

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

1. Start Visual Studio 2005.

2. From the File menu, select New Project. The New Project dialog box appears.

3. In the Project Types pane, select Visual Basic. In the Templates pane, select Console Application.

4. (Optional) In the Name box, type the name of the new application.

5. Click OK to load the Visual Basic console application template.

6. 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

7. On the View menu, click Code.-Or-Select the Module1.vb window to display the code window.

8. 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.Common
   

9. Insert the code that follows this procedure into the main program.

10. Run and build the application.

Example

'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