Check how much space used by Data file in Sql Server

select
 a.FILEID,
NAME = left(a.NAME,15),
 [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)) ,
  FILENAME = left(a.FILENAME,30)
from
 dbo.sysfiles a;