但Insus.NET想到的是，从下面的SQL语句，就可以查询到数据库大小。因此分享于此。
SELECT DB_NAME(database_id) AS [Database Name],[Name] AS [Logical Name],[Physical_Name] AS [Physical Name],((size * 8) / 1024) AS [Size(MB)],[differential_base_time] AS [Differential Base Time]
FROM sys.master_files
WHERE DB_NAME(database_id) IN('XXX')
GO