When we’re getting started with new field, some parts of this could be forgetable for us. We could get to the bottom of subject, learn it by rote, but have no idea what command has to be used for practice realization. For example, when we’ve realised how RDBMS work up to the B-tree conception. But also we could forget how to add user in MySQL or how to grant special privileges on Postgres.
For this kind of issues I’ve opened a special section on my blog. Here is my personal cheatsheets constitued on useful commands. One cheatsheet would be so enormous, thus I’m splitting it on few subjects. You’re welcome!