If you've already installed an update, do not install it again, only install the .sql files that are a higher version than the current one you are using. And yes, you'll have to do them one by one if you haven't installed any. Make sure you click on the database you are injecting into before using the .sql file for that database.
The changes for this version were (Cumulative Update 0021)
Code:Drop redundant data from `spell_proc_event` after recent spell chain changes.
Fix line ends
Some format string fixes
Improve detection removed ranks for spell in `spell_chain`