Understand the newest trend in database programming for developers working in Java, Kotlin, Clojure, and other JVM-based languages. This book introduces Reactive Relational Database Connectivity (R2DBC), a modern way of connecting to and querying relational databases from Java and other JVM languages. The book begins by helping you understand not only what reactive programming is, but why it is necessary. Then building on those fundamentals, the book takes you into the world of databases and the newly released Reactive Relational Database Connectivity (R2DBC) specification. Examples in the book are worked using the freely available MariaDB database along with MariaDB's vendor-implementation of the R2DBC service-provider interface (SPI). Following along with the examples and the provided example code helps prepare you to work with any of the growing number of R2DBC implementations for popular enterprise databases such as Oracle Database and SQL Server. You'll be well prepared for what is becoming the future of database access from Java and other languages built on the JVM. You will: Understand why R2DBC was created and how it utilizes the Reactive Streams API Understand the components of the R2DBC service-provider interface Create and manage reactive database connections and connection pools using an R2DBC client Programmatically execute queries on a relational database using an R2DBC client Effectively utilize transactions using an R2DBC client Build relational database-driven applications that are event-driven and non-blocking.