As I know, the usual steps to merge a branch into trunk:

1. checkout trunk/branch to local work copy dir

svn co svn://server/proj/trunk

svn co svn://server/proj/branch
2. merge the branch into trunk

cd trunk ## branch's local work copy dir

svn up

svn merge svn://server/proj/branch

svn diff ### now you can see what the branch changed

svn ci -m "merge branch into trunk" ## merging into the svn repo

Now my situation:

1. I have no local work copy dir (in don't want to )-- it means I don't have to check out the trunk and branch to local disk.
2. Merge the branch into trunk only by given URL (svn://server/proj/trunk && svn://server/proj/branch) -- it means the merging occurs on the svn server.

I have read so much doc about svn operation, but still I have no idea how to meet the need.

i hope some guy could help to solve the problem.