I see what you are getting at (and I actually do know the basics of SQL), but for embedded developers, i think it's much more important to know about the storage medium. Is it EEPROM or flash? What are pages and blocks? Do you need wear leveling? Can you erase bytes or only entire pages at a time? What is the write time og a page, a block and a byte? There are so many limitations in the way we have to store data, that I think it can be harmful to think of data as relational in the sense SQL teaches you, as it can wreck your performance and the lifetime of the storage medium.