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 that theory into practice. In this book, Chris Date explains relational theory in depth, and demonstrates through numerous examples and exercises how you can apply it to your use of SQL. This third edition has been revised, extended, and improved throughout. Topics whose treatment has been expanded include data types and domains, table comparisons, image relations, aggregate operators and summarization, view updating, and subqueries. A special feature of this edition is a new appendix on NoSQL and relational theory. Could you write an SQL query to find employees who have worked at least once in every programming department in the company? And be sure it’s correct? Why is proper column naming so important? Nulls in the database cause wrong answers. Why? What you can do about it? How can image relations help you formulate complex SQL queries? SQL supports "quantified comparisons," but they’re better avoided. Why? And how?Database theory and practice have evolved considerably since Codd first defined the relational model, back in 1969. This book draws on decades of experience to present the most up to date treatment of the material available anywhere. Anyone with a modest to advanced background in SQL can benefit from the insights it contains. The book is product independent. Table of Contents Chapter 1. Setting the Scene Chapter 2. Types and Domains Chapter 3. Tuples and Relations, Rows and Tables Chapter 4. No Duplicates, No Nulls Chapter 5. Base Relvars, Base Tables Chapter 6. SQL and Relational Alegebra I: The Original Operators Chapter 7. SQL and Relational Algebra II: Additional Operators Chapter 8. SQL and Constraints Chapter 9. SQL and Views Chapter 10. SQL and Logic Chapter 11. Using Logic to Formulate SQL Expressions Chapter 12. Miscellaneous SQL Topics Appendix A. The Relational Model Appendix B. SQL Departures from the Relational Model Appendix C. A Relational Approach to Missing Information Appendix D. A Tutorial D Grammar Appendix E. Summary of Recommendations Appendix F. NoSQL and Relational Theory Appendix G. Suggestions for Further Reading

Relational Database Index Design and the Optimizers

Ted Codd1970年的论文，题目翻译过来应该是 一种大型共享数据库的关系数据模型

DB - Access Path Selection in a Relational Database Management System.pdf In a high level query and data manipulation language such as SQL, requests are stated non-procedurally, without reference to access paths. This paper describes how System R chooses access paths for both simple (single relation) and complex queries (such as joins), given a user specification of desired data as a boolean expression of predicates. System R is an experimental database management system developed to carry ..

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