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