tailieunhanh - View Updating and Relational Theory

Views are virtual tables. That means they should be updatable, just as "real" orare. 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. | Theory In Practice View Updating Relational Theory Solving the View Update Problem O REILLY . Date Databases View Updating and Relational Theory 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. r 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. Chris Date is well known in the database industry for his ability to explain complex technical issues in a clear and understandable fashion. This book is a companion to his previous books for O Reilly SQL and Relational Theory 2nd edition and Database Design and Relational Theory both published in 2012. US CAN ISBN 978-1-449-35784-9 Twitter @oreillymedia oreilly O REILLY 9 7 81 449 357849 View Updating and Relational Theory Solving the View Update Problem C. J. Date .

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