This book is not a training book like the others ; this is not a self-study book, nor a reference manual, nor a practical manual... This book presents the database development environment to namely ORACLE, which aims to initiate and master the Oracle environment by presenting its architecture. Notes that I have used over the last decade to the Higher In-stitute of Management of Gabes (Tunisia) within the IT depart-ment applied this course to management. This book suitable for computer lessons for degree students and for students in Computer Engineering. The main chapters covered in this book are : - The Oracle architecture basics - The logical structure of ORACLE database - Transaction management - The Administrative Tools - Backup and Recovery