Many people follow the convention of writing SQL keywords in upper case. Few people enjoy using shift or caps lock to do it. This plugin fixes that.
Using vim-plug (or other similar package manager):
" put this in your ~/.vimrc, then run :PlugInstall
Plug 'jsborjesson/vim-uppercase-sql'
Install it and forget about it. When you type an SQL keyword in an SQL file, it will be automatically uppercased as you type, and it is smart enough to not uppercase stuff in comments or strings.