Preface
The Java programming language is now recognized as a major player in the enterprise computing landscape, and has been embraced whole-heartedly by Oracle Corporation, the world's leading database developer. SQLJ is an exciting technology that enables your Java programs to access a database. SQLJ allows you to embed Structured Query Language (SQL) the standard language used to access databases statements into your Java programs. You may already be familiar with the Java Database Connectivity (JDBC) API, another technology for adding SQL statements to a Java program. SQLJ has a number of advantages over JDBC:
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SQLJ is at a higher level of abstraction and has a simpler, more concise syntax than JDBC.
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SQLJ is strongly typed, and checks your embedded SQL statements for correctness, unlike JDBC.
With SQLJ, the compiler does more of the work for you because it checks your embedded SQL statements during compilation. JDBC, on the other hand, checks your SQL statements only when you actually run your program. Checking your statements up-front is a lot more desirable than checking them at runtime, and should result in your programs taking less time to develop.
You may also be familiar with Oracle's Pro*C product, which enables you to embed SQL statements in C programs. Embedding SQL statements using SQLJ is similar in concept to Pro*C.
You can add SQLJ statements to many types of Java programs, including standalone applications, applets, servlets, JavaServer Pages, Enterprise JavaBeans, and Oracle Java stored programs. I cover each of these types of Java programs in this book.
The Oracle8i and Oracle9i databases and the Oracle9i Internet Application Server (iAS) also contain a revolutionary new feature: an integrated Java execution environment known as the JServer (also referred to as the Oracle JVM). The JServer enables Java programs to be run directly from the database or the iAS. Before the introduction of the JServer, business logic had to be written in PL/SQL, Oracle's proprietary programming language. Now you can write your business logic using Java in the form of Oracle Java stored programs or Enterprise JavaBeans and deploy the logic to the JServer. I cover writing, deploying, and running JServer programs in this book.