处理 SMO 事件
某些服务器事件类型可以通过使用事件处理程序和 ServerConnection 对象来进行订阅。
当服务器上发生某些操作时，SQL Server 管理对象 (SMO) 中的许多实例类可以触发事件。
通过设置事件处理程序并订阅相关事件，可以以编程方式对这些事件进行处理。这种事件处理只是暂时性的，因为当 SMO 客户端程序退出时会删除所有的订阅。
ConnectionContext 事件处理
ServerConnection 对象支持若干种事件类型。事件属性必须设置为相应事件处理程序的实例，且必须将事件处理程序对象定义为用于处理事件的受保护函数。
事件订阅
您可以通过以下方法处理事件：编写事件处理程序类，创建该类的实例，将事件处理程序分配给父对象，然后订阅事件。
必须编写事件处理程序类才能处理事件。事件处理程序类可以包含多个事件处理程序函数，且只有在安装事件处理程序类后才能处理事件。事件处理程序函数将从可用于报告事件相关信息的 ServerEventNotificatificationArgs 参数接收关于事件的信息。
DatabaseEventSet 类和 ServerEventSet 类中列出了可以进行处理的数据库和服务器事件的类型。
示例
若要使用所提供的任何代码示例，您必须选择创建应用程序所需的编程环境、编程模板和编程语言。有关详细信息，请参阅 SQL Server 联机丛书中的“如何在 Visual Studio .NET 中创建 Visual Basic SMO 项目”或“如何在 Visual Studio .NET 中创建 Visual C# SMO 项目”。
在 Visual Basic 中注册事件处理程序并订阅事件处理
此代码示例演示如何设置事件处理程序以及如何订阅数据库事件。
'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 AdventureWorks2008R2 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 AdventureWorks2008R2 database.")
End Sub
Sub Main()
'Connect to the local, default instance of SQL Server.
Dim srv As Server
srv = New Server
'Reference the AdventureWorks2008R2 database.
Dim db As Database
db = srv.Databases("AdventureWorks2008R2")
'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
在 Visual C# 中注册事件处理程序并订阅事件处理
此代码示例演示如何设置事件处理程序以及如何订阅数据库事件。
//Create an event handler subroutine that runs when a table is created.
private void MyCreateEventHandler(object sender, ServerEventArgs e)
{
Console.WriteLine("A table has just been added to the AdventureWorks2008R2 database.");
}
//Create an event handler subroutine that runs when a table is deleted.
private void MyDropEventHandler(object sender, ServerEventArgs e)
{
Console.WriteLine("A table has just been dropped from the AdventureWorks2008R2 database.");
}
public void Main()
{
//Connect to the local, default instance of SQL Server.
Server srv;
srv = new Server();
//Reference the AdventureWorks2008R2 database.
Database db;
db = srv.Databases("AdventureWorks2008R2");
//Create a database event set that contains the CreateTable event only.
DatabaseEventSet databaseCreateEventSet = new DatabaseEventSet();
databaseCreateEventSet.CreateTable = true;
//Create a server event handler and set it to the first event handler subroutine.
ServerEventHandler serverCreateEventHandler;
serverCreateEventHandler = new ServerEventHandler(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.
DatabaseEventSet databaseDropEventSet = new DatabaseEventSet();
databaseDropEventSet.DropTable = true;
//Create a server event handler and set it to the second event handler subroutine.
ServerEventHandler serverDropEventHandler;
serverDropEventHandler = new ServerEventHandler(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.
Table tb;
tb = new Table(db, "Test_Table");
Column mycol1;
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.
int x;
int y;
for (x = 1; x <= 1000000000; x++) {
y = x * 2;
}
//Stop event handling.
db.Events.StopEvents();
}