（原）SQL Server 系統提供功能的三個疑惑

SELECT *
FROM [sys].[dm_db_index_physical_stats](NULL, NULL, NULL, NULL, NULL);
GO
 
SELECT *
FROM [sys].[dm_db_index_physical_stats](DEFAULT, DEFAULT, DEFAULT, DEFAULT, DEFAULT);
GO

DECLARE @nvcDefaultTraceFilePath AS NVARCHAR(4000);
SET @nvcDefaultTraceFilePath = N'';
 
SELECT @nvcDefaultTraceFilePath = [path]
FROM [sys].[traces]
WHERE [id] = 1;
 
SELECT *
FROM ::fn_trace_gettable(@nvcDefaultTraceFilePath, NULL);
 
SELECT *
FROM ::fn_trace_gettable(@nvcDefaultTraceFilePath, DEFAULT);
GO

SELECT *
FROM ::fn_virtualfilestats(1, NULL);
 
SELECT *
FROM ::fn_virtualfilestats(1, DEFAULT);

USE [tempdb];
GO
 
-- 創建隊列
IF OBJECT_ID(N'[dbo].[NotifyQueue]', 'SQ') IS NULL
BEGIN
    CREATE QUEUE [dbo].[NotifyQueue]
    WITH
        STATUS = ON
       ,RETENTION = OFF
END
GO
 
-- 創建服務
IF NOT EXISTS (SELECT 1 FROM [sys].[services] WHERE [name] = N'EventNotifyService') 
BEGIN
    CREATE SERVICE [EventNotifyService]
    ON QUEUE [dbo].[NotifyQueue] ([http://schemas.microsoft.com/SQL/Notifications/PostEventNotification]);
END
GO
 
-- 創建路由
IF NOT EXISTS (SELECT 1 FROM [sys].[routes] WHERE [name] = N'NotifyRoute')
BEGIN
    CREATE ROUTE [NotifyRoute]
    WITH 
        SERVICE_NAME = N'EventNotifyService'
       ,ADDRESS = N'LOCAL';
END
GO
 
-- 創建事件通知
IF NOT EXISTS (SELECT 1 FROM [sys].[event_notifications] WHERE [name] = N'CreateTableNotification')
BEGIN
    CREATE EVENT NOTIFICATION [CreateTableNotification]
    ON DATABASE
    FOR CREATE_TABLE
    TO SERVICE 'EventNotifyService', 'current database';
END
GO

IF OBJECT_ID(N'[dbo].[TableCreate]', 'U') IS NULL
BEGIN
    CREATE TABLE [dbo].TableCreate
    (
        Col1 INT
        ,Col2 VARCHAR(100)
        ,Col3 XML
    )
    ON [PRIMARY]
END
GO

SELECT 
    CAST([message_body] AS XML)
    ,message_enqueue_time
    ,*
FROM [dbo].NotifyQueue
GO