Learn X in Y Minutes is also my go to site for dealing with code in an unfamiliar language. It's managed to get me through learning Ruby and Coffeescript on the job, as well as learning PHP for university.

It's a pity that nobody has done one for SQL yet, I would've thought it would be in high demand.

It's good to quickly grasp basic syntax so you can read code in unfamiliar language. However, I don't think that it's a good resource to properly learn language.

You will often miss learning the philosophy of the language (the $language_name way of doing it), the different way of thinking about the problems that the language provides and similar details, which are often not necessary to read a snippet of code, but you want to understand it in order to properly learn the language and make the most of it.

SQL is a good example of it. It might be trivial to explain the syntax of most common SQL queries, but thinking in relations and tables is not natural to most people so there's not much you can do with basic syntax.

Also helped me a lot when I was learning Javascript from Codecademy. It introduced me to Eloquent Javascript book and Mozilla Developers Network.