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SQLJ: The 'open sesame' of Java database applications

The SQLJ standard now provides SQL-based database access from Java apps

By Shirley Ann Stern, JavaWorld.com, 05/01/99

ANSI and ISO standards for embedded SQL in general-purpose programming languages such as C, FORTRAN, COBOL, and ADA have been available for several years. SQL (Structured Query Language) itself dates back to the 1970s and today is accepted as the standard RDBMS language. SQL is powerful because it lets you work with data at the logical level. Implementation details can wait until you are ready to manipulate the data. Thousands of businesses and organizations worldwide use SQL to manipulate and manage large amounts of data effectively. Because of this widespread use of SQL, many businesses saw Java's lack of SQL support as a serious challenge for enterprise applications. Several leading database and application vendors met this challenge head-on and resolved to do something about it. The result was the formation of a consortium to define the SQL Java (SQLJ) standard.

This article will take a look at that standard, which is a set of programming extensions that define the interaction between the SQL database language and the Java programming language. SQLJ consists of a set of clauses that extend Java to include static SQL constructs. The SQLJ clauses are transformed by a translator into standard Java statements that access the database via a call interface.

The article will also explore the differences between SQLJ and JDBC. It's important to note that SQLJ supports static SQL only, and is complementary to JDBC. JDBC provides a fine-grained, dynamic interface from Java to the database.

The birth of a standard

About two years ago (April 1997 to be exact) Oracle, IBM, and Compaq's Tandem Division formed a consortium to define and advance the standardization of Java development for enterprise-level and server-side database applications. Other key database and application server vendors -- Sybase, Informix, and what was then called JavaSoft (now the Java Software Division at Sun) soon joined them. As a cofounder of the original SQLJ consortium, Oracle distributed a reference implementation of SQLJ to the other members in December 1997.

For the next year, the consortium members cooperated to formulate a comprehensive specification for submission to the ANSI/ISO standards body. They also went to great lengths to ensure the compatibility and interoperability of all SQLJ implementations from the various database vendors. In December 1998, this specification, now called SQLJ, was accepted as ANSI Standard X3.135.10-1998. This was a significant milestone for the Java language for two reasons:

• It provides integration of SQL and Java, thus reinforcing the adoption and use of Java for enterprise data-intensive applications
  
  
• It represents a landmark in multivendor cooperation and support for standards-based application development

What does the SQLJ Standard provide? The standard consists of three parts: The SQLJ Language Specification provides standard language syntax and semantics for embedding static SQL in Java programs. The Stored Procedure Specification defines standards for implementing database stored procedures and functions in Java. This will allow users who have written stored procedures in Java to easily migrate them between databases. The Stored Java Class Specification addresses standard ways to store Java datatypes and classes as objects in a database.

 

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