how to get LastModified time of a file system file and webserver file

my task is that i have to compare modified time of two file.one is in file system other is database file . which is most recently updated (which is newer).
details :
we have to check that which file is most recently updated .if database 's file is newer then we copy that file in to file system other wise we keep file system 's file as it is till database file is not updated
so that we can put the latest data in cache(which is in file system ) so we need not to access database again and again we just get data from our cache(or file system).

hope now you can answer well :

Please don't post the same question in multiple forums. It creates duplicate conversations and wastes the time of the people trying to help you.

Thanks,
Dave