Understanding SQL's underlying theory is the best way to guarantee that your SQL code is correct and your database schema is robust and maintainable. On the other hand, if you're not well versed in the theory, you can fall into several traps. In SQL and Relational Theory, author C.J. Date demonstrates how you can apply relational theory directly to your use of SQL. With numerous examples and clear explanations of the reasoning behind them, you'll learn how to deal with common SQL dilemmas, such as: Should database access granted be through views instead of base tables? Nulls in your database are causing you to get wrong answers. Why? What can you do about it? Could you 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 Edgar Codd originally defined the relational model back in 1969. Independent of any SQL products, SQL and Relational Theory draws on decades of research to present the most up-to-date treatment of the material available anywhere. Anyone with a modest to advanced background in SQL will benefit from the many insights in this book.
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.
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.
All of today’s mainstream database products support the SQL language, and relational theory is what SQL is supposed to be based on. But are those products truly relational? Sadly, the answer is no. This book shows you what a real relational product would be like, and how and why it would be so much better than what’s currently available. With this unique book, you will: Learn how to see database systems as programming systems Get a careful, precise, and detailed definition of the relational model Explore a detailed analysis of SQL from a relational point of view There are literally hundreds of books on relational theory or the SQL language or both. But this one is different. First, nobody is more qualified than Chris Date to write such a book. He and Ted Codd, inventor of the relational model, were colleagues for many years, and Chris’s involvement with the technology goes back to the time of Codd’s first papers in 1969 and 1970. Second, most books try to use SQL as a vehicle for teaching relational theory, but this book deliberately takes the opposite approach. Its primary aim is to teach relational theory as such. Then it uses that theory as a vehicle for teaching SQL, showing in particular how that theory can help with the practical problem of using SQL correctly and productively. Any computer professional who wants to understand what relational systems are all about can benefit from this book. No prior knowledge of databases is assumed.
SQL kann Spaß machen! Es ist ein erhebendes Gefühl, eine verworrene Datenmanipulation oder einen komplizierten Report mit einer einzigen Anweisung zu bewältigen und so einen Haufen Arbeit vom Tisch zu bekommen. Einführung in SQL bietet einen frischen Blick auf die Sprache, deren Grundlagen jeder Entwickler beherrschen muss. Die aktualisierte 2. Auflage deckt die Versionen MySQL 6.0, Oracle 11g und Microsoft SQL Server 2008 ab. Außerdem enthält sie neue Kapitel zu Views und Metadaten. SQL-Basics - in null Komma nichts durchstarten: Mit diesem leicht verständlichen Tutorial können Sie SQL systematisch und gründlich lernen, ohne sich zu langweilen. Es führt Sie rasch durch die Basics der Sprache und vermittelt darüber hinaus eine Reihe von häufig genutzten fortgeschrittenen Features. Mehr aus SQL-Befehlen herausholen: Alan Beaulieu will mehr vermitteln als die simple Anwendung von SQL-Befehlen: Er legt Wert auf ein tiefes Verständnis der SQL-Features und behandelt daher auch den Umgang mit Mengen, Abfragen innerhalb von Abfragen oder die überaus nützlichen eingebauten Funktionen von SQL. Die MySQL-Beispieldatenbank: Es gibt zwar viele Datenbankprodukte auf dem Markt, aber welches wäre zum Erlernen von SQL besser geeignet als MySQL, das weit verbreitete relationale Datenbanksystem? Der Autor hilft Ihnen, eine MySQL-Datenbank anzulegen, und nutzt diese für die Beispiele in diesem Buch. Übungen mit Lösungen: Zu jedem Thema finden Sie im Buch gut durchdachte Übungen mit Lösungen. So ist sichergestellt, dass Sie schnell Erfolgserlebnisse haben und das Gelernte auch praktisch umsetzen können.
Gain a solid understanding of T-SQL—and write better queries Master the fundamentals of Transact-SQL—and develop your own code for querying and modifying data in Microsoft SQL Server 2012. Led by a SQL Server expert, you’ll learn the concepts behind T-SQL querying and programming, and then apply your knowledge with exercises in each chapter. Once you understand the logic behind T-SQL, you’ll quickly learn how to write effective code—whether you’re a programmer or database administrator. Discover how to: Work with programming practices unique to T-SQL Create database tables and define data integrity Query multiple tables using joins and subqueries Simplify code and improve maintainability with table expressions Implement insert, update, delete, and merge data modification strategies Tackle advanced techniques such as window functions, pivoting and grouping sets Control data consistency using isolation levels, and mitigate deadlocks and blocking Take T-SQL to the next level with programmable objects
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.
How can you bring out MySQL’s full power? With High Performance MySQL, you’ll learn advanced techniques for everything from designing schemas, indexes, and queries to tuning your MySQL server, operating system, and hardware to their fullest potential. This guide also teaches you safe and practical ways to scale applications through replication, load balancing, high availability, and failover. Updated to reflect recent advances in MySQL and InnoDB performance, features, and tools, this third edition not only offers specific examples of how MySQL works, it also teaches you why this system works as it does, with illustrative stories and case studies that demonstrate MySQL’s principles in action. With this book, you’ll learn how to think in MySQL. Learn the effects of new features in MySQL 5.5, including stored procedures, partitioned databases, triggers, and views Implement improvements in replication, high availability, and clustering Achieve high performance when running MySQL in the cloud Optimize advanced querying features, such as full-text searches Take advantage of modern multi-core CPUs and solid-state disks Explore backup and recovery strategies—including new tools for hot online backups
Einführungen in MySQL gibt es viele. Wer aber größere MySQL-Server betreut, die verlässlich laufen müssen, egal was Programmierer oder Benutzer auf sie loslassen, der braucht weiter reichende Informationen. In High Performance MySQL beschreiben sechs anerkannte Experten mit langjähriger Erfahrung auf großen Systemen alle Stellschrauben, an denen MySQL-Admins drehen können, um Sicherheit, Performance, Datenintegrität und Robustheit zu erhöhen. Von Profis für Profis Hier geht es nicht um kleine Webauftritte mit Datenbankanbindung! Lernen Sie stattdessen fortgeschrittene Techniken kennen, mit denen Sie MySQLs Potenzial voll ausreizen können -- um große, skalierbare Systeme zu entwerfen, zu optimieren und zu sichern. Behandelt werden Benchmarking, Indizes, Storage-Engines, Replikationen, Lastverteilung und Hochverfügbarkeit, Backups, Sicherheit... und zu jedem Aspekt die richtigen Werkzeuge, mit denen sich Ihre Ziele am besten realisieren lassen. Praxiserprobt muss es sein Der eine ist MySQL-Guru bei Yahoo!, der andere Angestellter Nr. 25 bei MySQL AB und dort nacheinander für das MySQL-Manual, die Trainingskurse und die Entwicklung des Supports zuständig, wieder ein anderer war bei MySQL AB im High-Performance-Team – die Autoren dieses Buchs wissen, wovon sie sprechen. Graue Theorie finden Sie woanders, hier geht es um bewährte Techniken aus der Praxis. Die erste Auflage von „High Performance MySQL“ wurde hoch gelobt und hat schon unzähligen Lesern wertvolle Dienste geleistet. Nun war es an der Zeit, dieses anerkannte Handbuch einmal komplett zu aktualisieren, um nützliches Referenzmaterial zu erweitern, neue Features der Versionen MySQL 5.0 und 5.1 zu ergänzen und zahlreiche Themen wie die Optimierung der Storage-Engine InnoDB zu vertiefen.
Master the Underutilized Advanced Features of SQL and PL/SQL This hands-on guide from Oracle Press shows how to fully exploit lesser known but extremely useful SQL and PL/SQL features―and how to effectively use both languages together. Written by a team of Oracle ACE Directors, Real-World SQL and PL/SQL: Advice from the Experts features best practices, detailed examples, and insider tips that clearly demonstrate how to write, troubleshoot, and implement code for a wide variety of practical applications. The book thoroughly explains underutilized SQL and PL/SQL functions and lays out essential development strategies. Data modeling, advanced analytics, database security, secure coding, and administration are covered in complete detail. Learn how to: • Apply advanced SQL and PL/SQL tools and techniques • Understand SQL and PL/SQL functionality and determine when to use which language • Develop accurate data models and implement business logic • Run PL/SQL in SQL and integrate complex datasets • Handle PL/SQL instrumenting and profiling • Use Oracle Advanced Analytics and Oracle R Enterprise • Build and execute predictive queries • Secure your data using encryption, hashing, redaction, and masking • Defend against SQL injection and other code-based attacks • Work with Oracle Virtual Private Database Code examples in the book are available for download at www.MHProfessional.com. TAG: For a complete list of Oracle Press titles, visit www.OraclePressBooks.com
Datenbanken sind das beste Werkzeug, um wichtige Informationen im Auge zu behalten. Mit SQL k?nnen die vorhandenen Daten strukturiert und zielsicher abgefragt werden. In "SQL f?r Dummies" macht Allen G. Taylor die Leser mit der Abfragesprache SQL und dem aktuellen Standard SQL:2011 verst?ndlich und humorvoll vertraut. Er beginnt mit dem notwendigen Grundlagenwissen f?r den Aufbau eines Datenbankmanagementsystems und den SQL-Hauptkomponenten, zeigt auf, wie man die Daten erstellt, ordnet und abfragt und SQL-Anweisungen in Programme einbindet. Zudem erkl?rt er, wie SQL mit XML verkn?pft werden kann, um Websites mit einer Datenbank zu verbinden. Au?erdem gibt es jede Menge Profi-Informationen, wie man zum Beispiel Datenbanken und Daten sch?tzen kann und Fehler lokalisiert und behebt.
Der Keltenkrimi mit Schwester Fidelma Irland im 7. Jahrhundert: Im Kloster Imleach werden seit vielen Jahren die Reliquien des heiligen Ailbe aufbewahrt, die für Irland sowohl religiösen als auch politischen Symbolcharakter tragen. Seit kurzem sind sie verschwunden, ebenso ein Mönch aus der Klostergemeinschaft. Mit Geschick und scharfem Verstand gelingt es Schwester Fidelma und Bruder Eadulf, einer Gruppe von Verschwörern auf die Spur zu kommen, die vor nichts, nicht einmal Mord, zurückschrecken. "Eindeutig eine Konkurrenz für Ellis Peters_ Der historische Hintergrund ist großartig." Evening Standard

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