Structured Query Language
A language (or rather, a collection of very similar languages) for interacting with a database. Like PostScript and HTML, it is an interface language, in that it more likely to have been written by one program for use by another than to have been written “by hand.?
In rails, most of the SQL is handled by ActiveRecord, so you can go a long way without needed to know the gory details.
category: Glossary