Inside Relational Databases with Examples in Access - Tapa blanda

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Contents Should we tell you the whole story? Of course, there is an inevitable tension in trying to work like this. For example, in Chapter 16 we talk about referential integrity. There are - sentially six different flavors of referential integrity but Access only s- ports four of them (they are the most important ones however, so you aren’t missing out on too much). The problem is this. Should we tell you about the other two? If we do, as an Access user you have every right to be annoyed that we are telling you about a feature you can’t use. On the other hand, the six different types that we describe are part of the re- tional world and this book is about that world – we are not trying to teach you how to use Access, we are simply using Access to illustrate the relational model. Ultimately we decided to risk your ire and to describe all of the features of the relational model as we see it, even if Access doesn’t support all of them. One advantage of this approach is that if you need to use a different database engine you will almost certainly find the extra information useful. Incidentally, this is not meant to imply that Access is somehow lacking as a relational database engine. The reason we chose it for the first book is that it is such a good example of a relational database tool.

Contraportada

Inside Relational Databases was first published in 1997 and, rather to our surprise, rapidly reached the status of a classic work in the database field. Translated into three other languages and sold all over the world, it has helped thousands of people to understand the relational model that underpins all modern databases.

Inside Relational Databases has never been about how to use a particular database engine (Access, SQL Server, MySQL, whatever). Instead, it’s about the underlying way in which relational databases work. However it is very convenient if the book illustrates the relational model using the reader’s favorite product – such as Access. So, for the new edition we produced several different versions of the same book, each version based on a different database engine. The version in your hand is based around Access (hence the title). There are other versions based around SQL Server and MySQL.

You shouldn’t buy this book if you are looking for a book about how to use Access. You should buy this book if you have created databases but they don’t seem to work very well. Perhaps you:

·can’t retrieve the information that you want.

·have to type in the same information over and over again.

·type in data and it appears to go missing.

·ask questions and get answers that you know are wrong.

·can use Access but you don’t know exactly what to do with it.

·know that a relational database lets you create multiple tables in the database but you are uncertain why this is to your advantage.

Or perhaps you hear words in connection with databases like:

·normalization

·functional dependency

·inner join

·union

·redundant data

·data dictionary

·meta-data

·ER modeling

·transaction

·concurrency

·locking

You haven’t got the faintest idea what they mean and there is no one you can ask.

We have also taken the opportunity of the new edition to restructure the book significantly. I (Mark) continue to teach database design and practice, both to undergraduates and in the commercial world. Without doubt the most popular topic in the commercial world is how to make databases run faster (no great surprise there) so we have added an entire section of brand new material (more than 10% of the entire book) on that topic. The section on designing databases has been reorganized and expanded and we also re-read the entire book (several times) and brought it all up to date.