Getting started with MariaDB, by Daniel Bartholomew, is a good book for people who wants to approach MariaDB without knowing MySQL. While this book covers all basic topics, it provides a vast overview of what MariaDB is and can do. In other words: the text is not just about SQL queries.
The book also mentions topics that are not strictly related to MariaDB, but are important for MariaDB users; for example the importance of phisically securing a server, or how to secure a LAN.
The fundamental topics for a MariaDB newbie are covered: installation, configuration basics, user management, the most important SQL statements, backups, logs and more.
What is not in this book? A lot of things – that’s why it’s called Getting started with MariaDB! Many users will probably want learn more about each topic in the book, and should probably learn some MariaDB parts that are not explained in this book: keys, the optimizer, InnoDB. So, don’t stop learning after reading this book. But if you want to learn MariaDB, you can start from here.
For more books about MariaDB: Recommended MariaDB / MySQL Books.
The most complete source of information is the MariaDB KnowledgeBase.