数据库备份问题
这是存储过程CREATE PROCEDURE SP_SYSTEM_Backup(@Dir varchar(1024)) AS
DECLARE @Path varchar(2000)
DBCC SHRINKFILE(MSDLASLOG,0)
DBCC SHRINKFILE(MSDLASDATA,0)
SELECT @Path=@Dir+CONVERT(varchar(10),getdate(),120)+'.BAK'
BACKUP DATABASE MSDLAS TO DISK=@Path WITH INIT
GO
其中 DBCC SHRINKFILE(MSDLASLOG,0)
DBCC SHRINKFILE(MSDLASDATA,0)是清除日志文件,但当系统没有日志文件时就报错,请问怎样判断有无日志文件.