Views are virtual tables. That means they should be updatable, just as "real" or base tables are. In fact, view updatability isn’t just desirable, it’s crucial, for practical reasons as well as theoretical ones. But view updating has always been a controversial topic. Ever since the relational model first appeared, there has been widespread skepticism as to whether (in general) view updating is even possible.
In stark contrast to this conventional wisdom, this book shows how views, just like base tables, can always be updated (so long as the updates don’t violate any integrity constraints). More generally, it shows how updating always ought to work, regardless of whether the target is a base table or a view. The proposed scheme is 100% consistent with the relational model, but rather different from the way updating works in SQL products today.
This book can:
Help database products improve in the future
Help with a "roll your own" implementation, absent such product improvements
Make you aware of the crucial role of predicates and constraints
Show you how relational products are really supposed to behave
Anyone with a professional interest in the relational model, relational technology, or database systems in general can benefit from this book.
C.J. Date has a stature that is unique within the database industry. C.J. is a prolific writer, and is well-known for his best-selling textbook: An Introduction to Database Systems (Addison Wesley). C.J. is an exceptionally clear-thinking writer who can lay out principles and theory in a way easily understood by his audience.
Comments about oreilly View Updating and Relational Theory:
This is yet another book from C.J. Date on the relational theory. This time, C.J. takes you on the journey of View updates. The topic is controversial as this is not that obvious whether it is possible to perform view updates or not. C.J. approaches the topic from the relational theory point of view. That means, you will not find any SQL here. Some time ago while I was reading SQL and Relational Theory I claimed that Tutorial D language introduced by C.J. was an unnecessary element. In here, however, I think it serves it's purpose very well. Thanks to the specifics of Tutorial D, topics are easier to track by reader.
When it comes to the style of the book it's rather academic one. It means you will find here rather formal language, quite a lot of definitions and mathematically ascetic way of describing concepts presented in the book. I'd suggest this book to people who are experienced with relational theory (it's too tough for beginners) and for SQL experts who are looking for relational based explanation of problems that are currently not solved in SQL based databases.
I think this book is worth reading but you should be warned it is not an easy and pleasant read. It's rather demanding position in the field of database. However, if you are ready for that, go for it. Do not hesitate.
Bottom Line Yes, I would recommend this to a friend