To restore a file to the latest updated svn version, i.e. undo the local changes, you can use revert
:
svn revert file
To restore a file to an older version (revision XXX) use update
:
svn update -r XXX file
Warning: in both cases you will lose any local changes in the file because it will be overwritten.
To only view the older version of a file use cat
:
svn cat -r XXX file
And to view the differences with your local version of the file:
svn diff -r XXX file