數據庫常見的join方式有三種：inner join, left outter join, right outter join(還有一種full join，因不常用，本文不討論)。這三種連接方式都是將兩個以上的表通過on條件語句，拼成一個大表。以下是它們的共同點：
? 1. 關于左右表的概念。左表指的是在SQL語句中排在left join左邊的表，右表指的是排在left join右邊的表。
? 2. 在拼成的大表中，左表排在左邊，右表排在右邊。
? 3. on條件語句最好用=號對兩表相應的主外鍵進行連接。當然，也可以用其他操作符，如>, <, 來連接兩表的任一字段，此時的關系將非常復雜，連接后的記錄數也隨之而變得不確定。如果在一些特殊的場合中需要用到這種方式，必須通過簡單的實例加以確認，否則，連接結果很可能不是我們所想要的！
? 4. on條件語句不能省略。
? 5. 可以連鎖使用join，每次使用join都令另一表與當前的表或連接的結果相連接。
在下文中，用到了兩個表，"部門"表與"組織"表，其中，"部門"表有一名為"組織編號"的外鍵，指向"組織"表中的主鍵"編號"。
inner join
? 格式：select * from 部門 inner join 組織 on 部門.組織編號 = 組織.編號
? 目的：將兩表中符合on條件的所有記錄都找出來。
? 規律：
??? 1. 拼出的大表記錄不會增加。
??? 2. 如果左邊與右表的關系是一對多的關系，在選出的任一記錄中，假若右表有多個記錄與其對應，那么，連接后的左表，主鍵將不再唯一。
? 典型應用：將存在多關系的引用表放在左表，將存在一關系的被引用表放在右表，通過=號將主外鍵進行連接，通過對右表設定過濾條件，選出相應的且主鍵唯一的左表記錄。
? 備注：inner join 是默認的連接方式，可縮寫為join。
? 轉化為where子句：
??? select * from 部門, 組織 where 部門.組織編號 = 組織.編號
?
left outter join
? 格式: select * from 部門 left join 組織 on 部門.組織編號 = 組織.編號
? 格式: select * from 組織 left join 部門 on 組織.編號 = 部門.組織編號
? 目的：將左表的所有記錄列出，右表中只要符合on條件的，與左表記錄相拼合，不符合條件的，填以null值。
? 規律：
??? 1. 選出所有符合條件的左表，如果左邊與右表的關系是一對一的關系，則拼成的大表記錄不會改變。
?????? 如果左邊與右表的關系是多對一的關系，則拼成的大表記錄也不會改變。
?????? 如果左邊與右表的關系是一對多的關系，則拼成的大表記錄會增加。對于每一具有一對多關系的左表記錄，如果左表1：N與右表對應，那么會多出N-1條記錄。例如，如果左表第一條記錄1：3對應于右表，多出2條記錄。如果左表第二條記錄1：2對應于右表，則再多出1條記錄。這樣，總共多出3條記錄。其他類推。
??? 2. 如果左邊與右表的關系是一對多的關系，在選出的任一記錄中，假若右表有多個記錄與其對應，那么，連接后的左表，主鍵將不再唯一。
??? 3. 如果左邊與右表的關系是一對多的關系，對于左表任一記錄，如果右表沒有記錄與其相對應，則全部填以null值。
? 典型應用：將存在多關系的引用表放在左表，將存在一關系的被引用表放在右表，通過對右表設定過濾條件，選出相應的且主鍵唯一的左表記錄。
? 備注：left outter join可用left join代替。在有些數據庫中，如HSqlDb, 只能使用left join而不能使用left outter join。
? 轉化為where子句：
??? select * from 部門, 組織 where 部門.組織編號 = 組織.編號
right outter join
? 格式: select * from 部門 right join 組織 on 部門.組織編號 = 組織.編號
? 格式: select * from 組織 right join 部門 on 部門.組織編號 = 組織.編號
? 目的：將右表的所有記錄列出，左表中只要符合on條件的，與右表記錄相拼合，不符合條件的，填以null值。
? 規律：(與left outter join相反)
? 典型應用：可轉化成left outter join。例如
??? select * from 組織 right join 部門 on 部門.組織編號 = 組織.編號
??? 與
??? select * from 部門 left join 組織 on 部門.組織編號 = 組織.編號
??? 的效果一樣
? 備注：right outter join可用right join代替。在有些數據庫中，如HSqlDb, 沒有實現right join功能。
? 轉化為where子句：
??? select * from 部門, 組織 where 部門.組織編號 = 組織.編號
Session Descriptions
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Application developers are with what seems to be an unlimited number of approaches to integrating identity management and single sign-on(SSO).
This presentation will focus on the existing solutions that are available, commerical and open-source and examples from each to help you understand what solution might best work for you. Best practices and lessons learned from popular approaches will be covered too.
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Ajax has revolutionized Web application development in the short year since the term was coined. What is it all about? Why are we excited about a set of capabilities that have been sitting in our browser for years? What can you do with it? And, how can you do it?
Ajax , short for Asynchronous JavaScript and XML, is a technique for communicating with servers from within a web page without causing a page refresh.
This session provides:
- An introduction to Ajax and an orientation to the state of the ajaxian universe
- A demonstration of the basic ajaxian techniques through live coding. More advanced examples of Ajax will be demonstrated and deconstructed
You will understand:
- How the Google Maps UI is built (and why it isn't as hard as it looks)
- How Ajax can improve portals, community sites, and pretty much any other type of web application.
Furthermore, the issues surrounding how to create an Ajax application that doesn't turn into an unmaintainable pile of hacked up crap JavaScript will be discussed.
This talk will be presented by the founders of Ajaxian.com, a popular Ajax-related web portal.
Building Quality Applications with Ajax Frameworks
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Ajax techniques can lend tremendous richness to your Web UIs. But Ajax can be tedious and difficult to implement from scratch. Fortunately, there are a number of powerful frameworks that can make it much easier to do Ajax, including some that integrate with Java-based Web frameworks.
This session demonstrates (through live coding):
- The popular Prototype, Dojo, MochiKit, DWR and Scriptaculous frameworks, each of which offers unique abilities to enhance your applications. These frameworks can be used with any server-side framework
- Their use with Struts and JavaServer Faces applications
This talk will also discuss the state of Ajax support for JavaServer Faces via third-party JSF components and JSF-specific frameworks.
You will understand:
- How to easily add amazing Ajax effects to your Java-based Web application.
Distributed Caching: Essential Lessons
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Essential EJB 3.0 Persistence
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A crash course introduction to EJB 3.0 Persistence of Java Enterprise Edition 5.0. The goal of this session is to demonstrate how to apply the EJB 3.0 Persistence functionality in enterprise application development. Attendees will leave with enough information to get them started building enterprise applications using this new standard. The material will be presented using live demos of application development, testing, and deployment. The persistence capabilities both within and outside of an EJB container will be highlighted.
The open source reference implementation of the EJB 3.0 Persistence, TopLink Essentials, will be used in conjunction with the Eclipse Dali EJB ORM Project tools to build an end to end application illustrating common patterns and best practices.
Extreme Web Caching
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Flow with Continuations
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In many applications the typical short-comings of relational databases are covered up either by using database centric frameworks or even worse by using secondary storage. This shows in symptoms that we all know: Binaries go into a Filesystem, "unstructured" information is stored in XML, etc...
This session is geared to prove that a JCR compliant content repository is the ideal general purpose "Future Storage" for modern Applications that require commodity features like Versioning, Fulltext search, Hierarchy support, Ranking, Namespaces without sacrificing transactions, referencial integrity and scalability.
Expect real-life examples and code-snippets.
The Mobile Java Application Continuum
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Open Source SOA Using POJOs
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OSWorkflow
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Patterns in Service-Oriented Architectures
If this was buzzword bingo I probably would be an instant winner with this session title. Nevertheless, patterns and service-oriented architectures do have very interesting and relevant intersection points. Both terms are fashionable, somewhat blurry and often abused. Both terms are also very much about architecture and design trade-offs – the softer side of software development. Despite all the hype, SOA brings alternative architecture styles and programming models into the mainstream. We now write software using process engines, asynchronous message flow, rules engines, transformations etc. Each style comes with a collection of patterns that should be recognized and documented so that we can build effective solutions and discuss design trade-offs outside of specific technology choices and implementations.
Persistence with iBATIS - Hands On
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Portlet Development with JSF
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Productive Coder
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RAD That Ain't Bad: Domain Driven Development with Trails
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Refactoring Databases: Evolutionary Database Design
Scott Ambler
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Shale: The Next Struts?
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Software Visualization and Model Generation
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This talk applies the concepts of visualization and model generation to a broad range of usage scenarios, such as asynchronous messaging, software components and object-oriented applications.
The State of Web Frameworks
The last couple of years have seen a burst of both standardization and increased innovation in web application frameworks, to say nothing of the very quick uptake in popularity of AJAX. What does it mean for choosing server side technology? What does AJAX mean to existing frameworks? Should we all go back to rich clients instead? Come to this session for a high level overview of the present, and future, of building rich applications for the web.
Using Java Business Integration to Enable Composite Applications with ServiceMix
Bruce Snyder
Java Business Integration (JBI) is a simple API to a Normalized Message Service and Router along with a component model to facilitate the deployment and management of integration services. ServiceMix is a leading open source Enterprise Service Bus (ESB) and Service Oriented Architecture (SOA) toolkit based on the Java Business Integration
(JBI) specification. ServiceMix provides business integration capabilities using a complete JBI container and a host of JBI components including those for orchestration, rules, scheduling, transformation, validation and JBI transports including those for email, file, FTP, HTTP, JMS, RSS, VFS, VM and many more.
This session will focus on using ServiceMix in a composite application scenario that takes advantage of its JBI implementation and its use of other Java Enterprise Edition specifications.
Using the Apache License, not only can ServiceMix be deployed in a standalone configuration, but it is also fully integrated with Apache Geronimo or any other J2EE 1.4 compliant application server via the J2EE Connector Architecture (JCA). Fully embracing the Java Message Service (JMS) and Web Services standards allows ServiceMix to provide reliable and robust message delivery regardless of the message payload. The ServiceMix SOA platform provides for the managment of its JBI components via the Java Management eXtensions (JMX) using any JMX compliant management console.
XQuery for the Java Geek
Jason Hunter
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As a Java developer -- especially a server-side Java developer -- XQuery is key to searching and manipulating large XML repositories or performing any XML-centric task.
This talk introduces XQuery to the Java developer. I'll explain the XQuery language; I'll show how to call XQuery from Java (including coverage of JSR-225, the XQuery API for Java); and I'll show the XQuery and Java code behind a sample custom book publishing application.
As the creator of JDOM, I'll also explain when to use XQuery instead of JDOM, and when to use both.
XML, Schemas and Performance
Frank Cohen
The IT world is dealing with an explosion of XML schemas and the average Java engineer is not prepared with today's XML tools and techniques. For instance, SOAP, RSS, REST, SOA schemas and protocols, and AJAX are challenging developers every day. In this session Frank Cohen will give many examples of XML schema incompatibility, inefficient and needlessly bulky code, and poor performance and scalability that come with popular XML handling libraries, tools, and techniques. Cohen will show how new strategies for on-the-fly data schema transformation, SOA metadata persistence and versioning and policy-driven intelligent data caching are viable solutions.
BOFs
The Importance of Preserving Object Identity while Clustering
Jonas Bonér and Patrick Calahan, Terracotta
Clustering and other forms of distributed computing are not easy in Java. The proliferation of clustered caches in the market today illustrates the need for tools to make clustering in Java easier. The problems with most current solutions are that they break Java's natural programming model – with unnatural API's and breaking fundamental object identity. This Birds of a Feather session will focus on the importance of preserving object identity in a cluster, and will illustrate a runtime system that understands the developer's domain objects and clusters objects across a cluster transparently while maintaining object identity, using detailed code examples to illustrate the concepts.