This is a PDF of “Database System Concepts” by Korth, Silberschatz and Sudarshan. Silberschatz is the same person who co-authored the famous “Operating System Concepts” book (also called The Dinosaur Book).
Most of the material in the TMV is taken directly from this book. Like the OS concepts book, it has a very friendly language and covers topics in good detail.
One thing to remember however is that this is an older version and there is a newer edition of this book available, however this book should suffice for now.