SQL SERVER查询各数据库文件的IO

select b.name as dbname,c.name as fileName,c.physical_name,a.num_of_reads,a.num_of_writes, 
a.num_of_bytes_read,a.num_of_bytes_written,a.io_stall_read_ms,
a.io_stall_write_ms,a.io_stall   
from sys.dm_io_virtual_file_stats(null,null) a, 
sys.databases b,sys.master_files c 
where a.database_id=b.database_id 
and a.file_id=c.file_id 
and a.database_id=c.database_id