The Many Different Ways to Fetch Data in jOOQ

The jOOQ API is all about convenience, and as such, an important operation (the most important one?) like fetch() must come with convenience, too. The default way to fetch data is this: Result<Record1<String>> result = ctx.select(BOOK.TITLE) .from(BOOK) .fetch(); for (Record1<String> record : result) { // ... } It fetches the entire result set into memory … Continue reading The Many Different Ways to Fetch Data in jOOQ

Setting the JDBC Statement.setFetchSize() to 1 for Single Row Queries

An interesting hint by Vladimir Sitnikov has made me think about a new benchmark for jOOQ: https://twitter.com/lukaseder/status/1407662449331949568 The benchmark should check whether single row queries should have a JDBC Statement.setFetchSize(1) call made to them by default. The Javadoc of the method says: Gives the JDBC driver a hint as to the number of rows that … Continue reading Setting the JDBC Statement.setFetchSize() to 1 for Single Row Queries

How to Typesafely Map a Nested SQL Collection into a Nested Java Map with jOOQ

A really cool, recent question on Stack Overflow was about how to map a nested collection into a Java Map with jOOQ. In the past, I've blogged about the powerful MULTISET operator many times, which allows for nesting collections in jOOQ. This time, instead of nesting data into a List<UserType>, why not nest it in … Continue reading How to Typesafely Map a Nested SQL Collection into a Nested Java Map with jOOQ

A Quick and Dirty Way to Concatenate Two Vaguely Related Tables in SQL

Every now and then I run across a use case for the arcane NATURAL JOIN SQL operator, and I'm even more delighted when I can make that a NATURAL FULL JOIN. A few past blog posts on the subject include: Use NATURAL FULL JOIN to compare two tables in SQLImpress Your Coworkers With the Incredible … Continue reading A Quick and Dirty Way to Concatenate Two Vaguely Related Tables in SQL

Nested Transactions in jOOQ

Since jOOQ 3.4, we have an API that simplifies transactional logic on top of JDBC in jOOQ, and starting from jOOQ 3.17 and #13502, an equivalent API will also be made available on top of R2DBC, for reactive applications. As with everything jOOQ, transactions are implemented using explicit, API based logic. The implicit logic implemented … Continue reading Nested Transactions in jOOQ

How to Fetch Sequence Values with jOOQ

A lot of RDBMS support standard SQL sequences of some form. The standard SQL syntax to create a sequence is: CREATE SEQUENCE s; The following is how you could fetch a value from this sequence, using jOOQ, assuming you're using the code generator: // import static com.example.generated.Sequences.*; System.out.println(ctx.fetchValue(S.nextval())); The sequence expression translates to a variety … Continue reading How to Fetch Sequence Values with jOOQ

Various Meanings of SQL’s PARTITION BY Syntax

For SQL beginners, there's a bit of an esoteric syntax named PARTITION BY, which appears all over the place in SQL. It always has a similar meaning, though in quite different contexts. The meaning is similar to that of GROUP BY, namely to group/partition data sets by some grouping/partitioning criteria. For example, when querying the … Continue reading Various Meanings of SQL’s PARTITION BY Syntax

Use MULTISET Predicates to Compare Data Sets

Questions that might be a bit more difficult to solve using ordinary SQL are questions of the kind: What films have the same actors as a given film X? As always, we're using the sakila database for this example. What would be a possible way to solve this with SQL (for example, PostgreSQL, to be … Continue reading Use MULTISET Predicates to Compare Data Sets

Projecting Type Safe Nested TableRecords with jOOQ 3.17

A long standing feature request has seen little love from the jOOQ community, despite a lot of people probably wanting it. It goes by the unimpressive title Let Table<R> extend SelectField<R>: https://github.com/jOOQ/jOOQ/issues/4727 What does the feature mean, specifically? The awesome PostgreSQL Let's have a look at a really cool PostgreSQL feature. In PostgreSQL, it is … Continue reading Projecting Type Safe Nested TableRecords with jOOQ 3.17

jOOQ 3.16 and Java EE vs Jakarta EE

A tidal wave is rippling through the Java ecosystem. It is the renaming of javax to jakarta package names. Now, while we've all been whining and complaining and shaking our heads due the clash between corporate legal and engineering interests, eventually it's time to move on and learn what this means specifically, for jOOQ. jOOQ … Continue reading jOOQ 3.16 and Java EE vs Jakarta EE