Time And Relational Theory

Time and Relational Theory provides an in-depth description of temporal database systems, which provide special facilities for storing, querying, and updating historical and future data. Traditionally, database management systems provide little or no special support for temporal data at all. This situation is changing because: Cheap storage enables retention of large volumes of historical data in data warehouses Users are now faced with temporal data problems, and need solutions Temporal features have recently been incorporated into the SQL standard, and vendors have begun to add temporal support to their DBMS products Based on the groundbreaking text Temporal Data & the Relational Model (Morgan Kaufmann, 2002) and new research led by the authors, Time and Relational Theory is the only book to offer a complete overview of the functionality of a temporal DBMS. Expert authors Nikos Lorentzos, Hugh Darwen, and Chris Date describe an approach to temporal database management that is firmly rooted in classical relational theory and will stand the test of time. This book covers the SQL:2011 temporal extensions in depth and identifies and discusses the temporal functionality still missing from SQL. Understand how the relational model provides an ideal basis for taming the complexities of temporal databases Learn how to analyze and evaluate commercial temporal products with this timely and important information Be able to use sound principles in designing and using temporal databases Understand the temporal support recently added to SQL with coverage of the new SQL features in this unique, accurate, and authoritative reference Appreciate the benefits of a truly relational approach to the problem with this clear, user friendly presentation

SQL is full of difficulties and traps for the unwary. You can avoid them if you understand relational theory, but only if you know how to put the theory into practice. In this insightful book, author C.J. Date explains relational theory in depth, and demonstrates through numerous examples and exercises how you can apply it directly to your use of SQL. This second edition includes new material on recursive queries, “missing information” without nulls, new update operators, and topics such as aggregate operators, grouping and ungrouping, and view updating. If you have a modest-to-advanced background in SQL, you’ll learn how to deal with a host of common SQL dilemmas. Why is proper column naming so important? Nulls in your database are causing you to get wrong answers. Why? What can you do about it? Is it possible to write an SQL query to find employees who have never been in the same department for more than six months at a time? SQL supports “quantified comparisons,” but they’re better avoided. Why? How do you avoid them? Constraints are crucially important, but most SQL products don’t support them properly. What can you do to resolve this situation? Database theory and practice have evolved since the relational model was developed more than 40 years ago. SQL and Relational Theory draws on decades of research to present the most up-to-date treatment of SQL available. C.J. Date has a stature that is unique within the database industry. A prolific writer well known for the bestselling textbook An Introduction to Database Systems (Addison-Wesley), he has an exceptionally clear style when writing about complex principles and theory.

"This Master Class video describes and explains that theoretical ideal- which, interestingly, is 100 percent consistent with the classical relational model-in depth. It also discusses, in depth, the new temporal support to be found in the SQL standard. This video includes five major parts: A review of relational concepts, laying the foundations, building on the foundations, and SQL support."--Resource description page.

A reinterpretation of world politics drawing on Chinese cultural and philosophical traditions to argue for a focus on relations amongst actors, rather than on the actors individually.

This important and innovative book explores a new direction in psychoanalytic thought that can expand and deepen clinical practice. Relational psychoanalysis diverges in key ways from the assumptions and practices that have traditionally characterized psychoanalysis. At the same time, it preserves, and even extends, the profound understanding of human experience and psychological conflict that has always been the strength of the psychoanalytic approach. Through probing theoretical analysis and illuminating examples, the book offers new and powerful ways to revitalize clinical practice.

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.

A review of relational concepts -- An overview of Tutorial D -- Time and the database -- What is the problem? -- Intervals -- Operators on intervals -- The EXPAND and COLLAPSE operators -- The PACK and UNPACK operators -- Generalizing the relational operators -- Database design -- Integrity constraints 1 : candidate keys and related constraints -- Integrity constraints 2 : general constraints -- Database queries -- Database updates -- Stated times and logged times -- Point and interval types revisited.

Because databases often stay in production for decades, careful design is critical to making the database serve the needs of your users over years, and to avoid subtle errors or performance problems. In this book, C.J. Date, a leading exponent of relational databases, lays out the principles of good database design.