Get the database space used in sqlserver

select
    a.FILEID,
    [FILE_SIZE_MB] =
        convert(decimal(12,2),round(a.size/128.000,2)),
    [SPACE_USED_MB] =
        convert(decimal(12,2),round(fileproperty(a.name,'SpaceUsed')/128.000,2)),
    [FREE_SPACE_MB] =
        convert(decimal(12,2),round((a.size-fileproperty(a.name,'SpaceUsed'))/128.000,2)) ,
    NAME = left(a.NAME,15),
    FILENAME = left(a.FILENAME,30)
from
    dbo.sysfiles a