SQL查詢服務器硬盤剩余空間

DECLARE @tb1 Table
( 
drive varchar(20), 
[MB 可用空間] varchar(20)
) 
INSERT INTO @tb1 
Exec master.dbo.xp_fixeddrives
select drive , CAST( CAST((CAST([MB 可用空間] as decimal(9,2))/1024 ) as decimal(9,2)) as varchar)+'G' as 剩余空間 from @tb1