Database management systems are the electronic filing cabinets that help individuals and organizations to manage the mass of information they process each day. With a well-designed database, information can be easily stored, updated, accessed, and collated. For example, a freight company can use a database to record data associated with each shipment, such as the sender and recipient, origin and destination, dispatch and delivery time, current location, and shipping fee. Some of this information needs to be updated as the shipment progresses. The current status of a shipment can be read off the database at any time, and data on all shipments can also be summarized into regular reports.

The Web has inspired a new generation of database use. It’s now very easy to develop and publish multi-user applications that don’t require any custom software to be installed on each user’s computer. Adding a database to a web application allows information to be automatically collected and used. For example, a customer can visit an online shopping site, see what’s in stock, place an order, submit payment information, and track the order until the goods are delivered. He can also place advance orders for goods that aren’t available, and submit reviews and participate in discussions on items he has purchased. If all goes well, the site’s staff doesn’t need to intervene in any of these actions; the less staff intervention required during normal operation, the more scalable the application is to large numbers of users. The staff are then free to do more productive tasks, such as monitoring sales and stock in real time, and designing special promotions based on product sales.

Both authors of this book have always been interested in using computers as a tool to make things faster, more efficient, and more effective. Over the past few years we’ve repeatedly found that the MySQL database management system—and the PHP and Perl programming languages—provide a perfect platform for serious applications such as managing research records and marking student assignments, and not-so-serious ones like running the office sweepstakes. On the way, we’ve learned a lot of lessons that we’d like to pass on; this book contains the tips that we think most readers will find useful on a daily basis.