Returns a timestamp for the date and time of the last modification of the file filename. If no filename is specified, the function will refer to the currently read table file.
Examples:
filetime( 'xyz.xls' )
Will return the timestamp of the last modification of the file xyz.xls.
Load *, filetime() as X from abc.txt ;
Will return the date and time of the last modification of the file (abc.txt) as a timestamp in field X in each record read.
