sqlj-lang

Walk through the generated DB2 application

The runnable starting point is the installed plugin’s New Project wizard. Follow getting started to install the package, create/import the demo and complete its first DB2 startup. No private source clone or separate example download is required.

Follow one request through the code

  1. Open TodoController.java under src/main/java and find its repository use. Ctrl+B on TodoRepository should open TodoRepository.sqlj under src/main/sqlj, rather than requiring you to edit generated Java.
  2. In the SQLJ repository, inspect the named iterator declaration. Its columns become modeled Java accessor methods for completion and navigation.
  3. Follow findAll(): the repository obtains a JDBC connection from the configured DataSource, wraps it in a SQLJ context, executes a query into an iterator, traverses rows and creates Todo objects. The generated code shows its cleanup.
  4. Find a host bind such as :title or :taskId. Ctrl+B should navigate to its Java declaration. In a disposable copy, try an invalid member name and confirm highlighting, then undo the change.
  5. Run the application and open http://localhost:8080. Add a task, mark it complete, reopen it, try a filter and delete a task. Flyway supplied the schema and seed records; SQLJ did not create them merely by opening the file.

Understand the build boundary

The .sqlj file is the source you edit. Maven invokes the IBM translator to create Java and SQLJ profile resources, compiles Java and installs source maps at process-classes. IDE assistance can work before translation, but execution needs the complete build/runtime. The starter POM explicitly translates its repository input; adding another .sqlj requires extending that build input configuration.

For an IDE run/debug select SQLJ Demo (Maven + SMAP). To package from a terminal:

mvn clean package

Use the debugger walkthrough to try stepping, watches, conditions and logpoints in the application.

Make one small SQLJ change

In a disposable demo copy, change a SQL query’s ordering while keeping the selected columns compatible with the iterator, then rebuild and verify the page result. Do not change generated Java. If a build rejects the SQL, retain its first translator/database message; the IDE is not the final authority on DB2 semantics.

Continue with iterators and connection/execution contexts.

This site is open source. Improve this page.