If you don't use some kind of source control management or version control system and your working with a team of 2 or more, then we strongly advise you do.
This article covers the simple task of ignoring files on svn update. In our case, we needed to exclude our application's config files. This way we can have a DEV, QA and LIVE environment, all easily updated with svn while maintaining there respective config files.
This is done by editing the svn:ignore property
svn propedit svn:ignore ./the_folder
This will load the editor specified in the env var SVN_EDITOR.
SVN_EDITOR='"/bin/vi"' export SVN_EDITOR
This will set VI as your default editor for SVN, you may set it to either nano or emacs, your choice
Once you run the svn propedit command, it will fire up your specified editor, here you can specify either the entire folder or specific files
*or
database_config.php
I don't think it supports regular expression however you can use the * wildcard. Below is a script that ignores all files ending in config.php
*config.php