Introduction to SQL: Mastering the Relational Database Language, Fourth Edition/20th Anniversary Edition

Chapter 27. Transactions and Multi-User Usage

Introduction

So far in this book, we have assumed that you are the only user of the database. If you do the examples and exercises at home, that assumption is probably correct. But if you work with SQL in your company, for example, the odds are good that you share the database with many other users. We call this multi-user usage as opposed to single-user usage. Actually, in a multi-user environment, you should not be aware that other users are accessing the database concurrently because SQL hides this from you as much as possible. Still, the following question might occur to you: What will happen if I access a row that is already in use by someone else? In short, that question is the subject of this ...