JOOQ Facts: SQL functions made easy

The JDBC API has always  been cumbersome and error-prone and I’ve never been too fond of using it. The first major improvement was brought by the Spring JDBC framework which simply revitalized the JDBC usage with its JdbcTemplate or the SqlFunction classes, to name a few. But Spring JDBC doesn’t address the shortcoming of using string function or input parameters names and this opened the door for type-safe SQL wrappers such as JOOQ.

JOOQ is the next major step towards a better JDBC API and ever since I started using it I knew there was no turning back. JOOQ became my number one choice for building dynamic queries and recently it became my standard SQL function wrapper.

To prove it, I will start with a simple SQL function:


While you should never ever use your database for formatting a Date, since that’s the job of your application logic, for the sake of testing let’s concentrate on the input and output variable types, since that’s where JOOQ excels over any other JDBC APIs.

With Spring this is how I’d call it:

private DataSource localTransactionDataSource;

public String formatTimestamp() {
	SqlFunction<String> sqlFunction =
		new SqlFunction<String>(localTransactionDataSource, "{ ? = call FORMAT_TIMESTAMP(?) }", new int[]{Types.TIMESTAMP});
	return (String) sqlFunction.runGeneric(new Date[]{new Date()});

This is way better than standard JDBC API but I don’t like to use String parameter names or casting the return value. Since HSQLDB doesn’t support using OUT parameters for SQL functions I cannot make use of StoredProcedure or SimpleJdbcCall which might have offered a better alternative to the SqlFunction example.

Let’s see how you can call it with JOOQ:

private DSLContext localTransactionJooqContext;

public String formatTimestamp() {
	FormatTimestamp sqlFunction = new FormatTimestamp();
	sqlFunction.setInTime(new Timestamp(System.currentTimeMillis()));
	return sqlFunction.getReturnValue();

In my opinion this is the most elegant SQL function wrapper I’ve ever used so far and that’s why it became my standard approach for calling SQL functions and procedures.

Code available on GitHub.

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4 thoughts on “JOOQ Facts: SQL functions made easy

  1. There are even more goodies! :-)

    HSQLDB does support OUT parameters. I don’t know what this SourceForge issue is talking about.
    While your usage of the “explicit” Routine API works well, you can also use the generated Routines helper class. This will allow you to write:

    String string = Routines.formatTimestamp(configuration, timestamp);

    You can also use such a function inline in your SQL statements:

    • Ah, silly me. You were talking about OUT parameters for functions. Yes, I think that’s only supported in Oracle.

      • … (and PostgreSQL. I think I’ll start thinking before writing, now)

      • I’ve been using a bulk-delete SQL function implemented on top of Spring StoredProcedure, and it worked for both Oracle and PostgreSQL, the two databases we’ve been supporting. I couldn’t make it work for the current HSQLDB (2.2.8), but maybe a new version will address this limitation.

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