How to discard local changes in an SVN checkout?

Just use the svn revert command, for example:

svn revert some_file.php

It is (as every other svn command) well documented in the svnbook resource or man page, or even with the svn help command.

You need to revert all the changes using the svn revert command:

• Revert changes to a file: svn revert foo.c
• Revert a whole directory of files: svn revert --recursive .

To discard local changes in one particular file:

$ svn revert example_directory/example_file.txt

To discard local changes in one particular folder:

$ svn revert -R example_directory/