View Updating and Relational Theory (Paperback)

C. J. Date

View Updating and Relational Theory (Paperback)

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商品描述

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.

商品描述(中文翻譯)

觀點是虛擬表格。這意味著它們應該是可更新的，就像「真實」或基本表格一樣。事實上，觀點的可更新性不僅是可取的，而且是至關重要的，無論是出於實際原因還是理論原因。但觀點的更新一直是一個有爭議的話題。自從關聯模型首次出現以來，人們普遍懷疑（一般而言）觀點的更新是否可能。

與這種常識形成鮮明對比的是，本書展示了觀點，就像基本表格一樣，可以始終被更新（只要更新不違反任何完整性約束）。更一般地說，它展示了更新應該始終如一地工作，無論目標是基本表格還是觀點。所提出的方案與關聯模型完全一致，但與當今SQL產品中的更新方式有所不同。

本書可以：
- 幫助未來改進數據庫產品
- 在缺乏這種產品改進的情況下，幫助自行實施
- 讓您意識到謂詞和約束的關鍵作用
- 展示關聯產品真正應該如何運作

任何對關聯模型、關聯技術或數據庫系統有專業興趣的人都可以從本書中受益。

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