As a SysAdmin who "wears all the hats", I find myself increasingly pulled into database projects. I took one database course back in college and since then I've always scoured resources online (like StackExchange) when working on databases/SQL. But there's always something I do and I'm never sure about such as security & perfomance in large environments.
If a DBA were to fully design/create a database/schema from scratch and maintain it from then on, what do you expect a DBA know? What are things a DBA should never do, or always ensure it is done? What have you experienced in a professional environment that education never prepared you for?