| We have chosen to use Oracle for most of the examples in this book due to its high compliance to the ANSI standard; however, we have also shown examples from MySQL, Sybase, Microsoft SQL Server, and dBASE. Oracle was also used the most due to the fact that Oracle is one of the most popular relational database products today. The use of MySQL for hands-on exercises was chosen so that all readers may participate, with minimal confusion in converting SQL syntax into the proper syntax of the database each reader is using. MySQL was chosen for exercises because it is an open source database (free) and its syntax is very similar to that of Oracle SQL, which was the primary database used for book examples. MySQL can be obtained for free, and installed with ease. Additionally, MySQL is compatible with most operating system platforms. The trade-off of using an open source database such as MySQL is that it is not as powerful, and not as compliant to the ANSI SQL standard, as most implementations provided by vendors such as Oracle, Microsoft, and IBM. However, MySQL is an excellent database product for training and some production environments. In Appendix B,we show you how to obtain and install MySQL. Once installed on your computer, MySQL can be used for most of the exercises in this book. Unfortunately, because MySQL is not fully ANSI SQL compliant, MySQL exercises are not available for every subject.  | We have attempted to point out all instances where subject matter does not apply to MySQL. A No MySQL icon is included next to code examples in each day's lesson that do not work with MySQL. If examples are not annotated with this icon, you can try these examples with MySQL. |
 | As stated, there are some differences in the exact syntax among implementations of SQL. For example, if you attempt to execute some examples in this book, you may have to make minor modifications to fit the exact syntax of the implementation that you are using. We have tried to keep all the examples compliant with the standard; however, we have intentionally shown you some examples that are not exactly compliant. The basic structure for all the commands is the same. To learn SQL, you have to start with an implementation using practical examples. For hands-on practice, we use MySQL. If you have access to another database implementation such as Oracle, we encourage its use for hands-on exercises. You should be able to emulate the database and examples used in this book without very much difficulty. Any adjustments that you may have to make to the examples in this book to fit your implementation exactly will only help you to better understand the syntax and features of your implementation. | Good luck!  |
