ANTI JOIN is a very useful operator from relational algebra. Regrettably, only few dialects support it in terms of SQL syntax, as we’ve written earlier. In jOOQ, you can write it as follows: If your RDBMS supports this natively (e.g. ClickHouse, Databricks), then it is rendered as such. Otherwise, j...

Some SQL operators are as esoteric as they’re powerful. One of the oldest operator that you’ve likely hardly ever used in real world applications is NATURAL JOIN which is the default in relational algebra. We’ve covered a funky use-case for NATURAL JOIN earlier on this blog. The main reason why it’s...

One of jOOQ’s most popular feature is the out-of-the-box debug logging experience. jOOQ developers find this feature very useful when developing their applications. Assuming you run a jOOQ query and configure your logger to print DEBUG log output: When this query is executed, your log output might c...

When implementing the awesome MULTISET operator in jOOQ, its implementation mostly relied on SQL/JSON support of various RDBMS. In short, while standard SQL supports nested collections via ARRAY or MULTISET operators like this: This is poorly supported in most RDBMS, so jOOQ emulates it using SQL/JS...

ARRAY types are a part of the ISO/IEC 9075 SQL standard. The standard specifies how to: But it is very unopinionated when it comes to function support. The ISO/IEC 9075-2:2023(E) 6.47 <array value expression> specifies concatenation of arrays, whereas the 6.48 <array value function> section lists a ...

RIGHT JOIN is an esoteric feature in the SQL language, and hardly ever seen in the real world, because almost every RIGHT JOIN can just be expressed as an equivalent LEFT JOIN. The following two statements are equivalent: It’s not unreasonable to expect these two statements to produce the same execu...

Every product manager knows this situation: This is such a common pattern, and while it’s perfectly understandable for such a user to request this, it is so terribly wrong to give in to this user’s request. Why is it wrong? The features are unrelated Most of the time, the two features X1 and X2 are ...

New dialects: jOOQ 3.20 ships with 2 new experimental dialects: ClickHouse is a fast-moving SQL dialect with a historic vendor-specific syntax that is gradually migrated to a more standards compliant alternative, which is why our support is still experimental. A lot of behaviours differ from what on...

A cool standard SQL:2003 feature is the aggregate FILTER clause, which is supported natively by at least these RDBMS: The following aggregate function computes the number of rows per group which satifsy the FILTER clause: This is useful for pivot style queries, where multiple aggregate values are co...

I’ve blogged about generic ways of getting top 1 or top n per category queries before on this blog. An Oracle specific version in that post used the arcane KEEP syntax: This is a bit difficult to read when you see it for the first time. Think of it as a complicated way to say … Continue reading Gett...

In a previous blog post, we’ve advertised the use of SQL EXISTS rather than COUNT(*) to check for existence of a value in SQL. I.e. to check if in the Sakila database, actors called WAHLBERG have played in any films, instead of: Do this: (Depending on your dialect you may require a FROM DUAL clause,...

One of jOOQ’s key features so far has always been to render pretty much exactly the SQL that users expect, without any surprises – unless some emulation is required to make a query work, of course. This means that while join elimination is a powerful feature of many RDBMS, it isn’t part of jOOQ’s fe...

jOOQ 3.19 finally delivers on a set of features that will greatly simplify your queries further, after jOOQ 3.11 introduced implicit to-one joins: What are these features? Many ORMs (e.g. JPA, Doctrine, jOOQ 3.11 and others) support “path joins” (they may have different names for this concept). A pa...

In MySQL, you cannot do this: The UPDATE statement will raise an error as follows: SQL Error [1093] [HY000]: You can’t specify target table ‘t’ for update in FROM clause People have considered this to be a bug in MySQL for ages, as most other RDBMS can do this without any issues, including MySQL clo...

New Dialects It’s been a few releases since we’ve added support for new dialects, but finally some very interesting RDBMS of increasing popularity have joined the jOOQ family including: These dialects are available in all jOOQ editions. New dialect versions In addition to these entirely new dialects...

Do you need to add a JDBC driver to your application, and don’t know its Maven coordinates? This blog post lists the most popular drivers from the jOOQ integration tests. Look up the latest versions directly on https://central.sonatype.com/ with parameters g:groupId a:artifactId, for example, the H2...

jOOQ’s DAO API is one of jOOQ’s most controversial features. When it was first implemented, it was implemented merely: There’s a strong hint about the third bullet given how popular Spring Data’s repository “pattern” is. A lot of developers just want to quickly fetch and store data, without giving i...

Need to connect to your RDBMS with JDBC and don’t have the JDBC connection URL or driver name at hand? No problem, just look up your RDBMS below:

Java’s package private visibility is an underrated feature. When you omit any visibility modifier in Java, then the default (for most objects) is package private, i.e. the object is visible only to types in the same package: In fact, a compilation unit (the .java file) can contain multiple such clas...

Microsoft T-SQL supports a language feature called table-valued parameter (TVP), which is a parameter of a table type that can be passed to a stored procedure or function. For example, you may write: This function takes a table-valued parameter (TVP), and produces a result set containing the cross p...

Occasionally, you want to write a SQL query and fetch a hierarchy of data, whose flat representation may look like this: The result might be: |id |parent_id|label | |---|---------|-------------------| |1 | |C: | |2 |1 |eclipse | |3 |2 |configuration | |4 |2 |dropins | |5 |2 |features | |7 |2 |plugin...

DiagnosticsListener improvements A lot of additional diagnostics have been added, including the automated detection of pattern replacements, helping you lint your SQL queries irrespective of whether you’re using jOOQ to write your SQL, or if you’re using it as a JDBC / R2DBC proxy for an existing ap...

jOOQ 3.15 introduced the concept of an ad-hoc converter, a converter that is applied “ad-hoc” to a single query. It uses the same underlying mechanisms as any ordinary Converter that is attached to generated code for use in every query. An example of such an ad-hoc converter is this: While there are...

One of the more frequent questions about jOOQ is how to write a derived table (or a CTE). The jOOQ manual shows a simple example of a derived table: In SQL: In jOOQ: And that’s pretty much it. The question usually arises from the fact that there’s a surprising lack of type safety when working … Cont...

I’ve found an interesting question on Twitter, recently. Is there any performance impact of using FILTER in SQL (PostgreSQL, specifically), or is it just syntax sugar for a CASE expression in an aggregate function? As a quick reminder, FILTER is an awesome standard SQL extension to filter out values...

One of MySQL 8’s biggest improvements is the support of window functions. As I always said in conferences, there’s SQL before window functions and SQL after window functions. Once you start using them, you’ll use them everywhere. Some of you poor souls are unfortunate enough to be stuck on MySQL 5.7...

Previously on this blog, I’ve written a post explaining why you should use jOOQ’s code generator, despite the possibility of using jOOQ without it. In a similar fashion, as I’ve answered numerous jOOQ questions on Stack Overflow, where someone used jOOQ to build a query, but then executed it elsewhe...

jOOQ already has a LoggingConnection (see also the manual), which acts as a JDBC proxy Connection to log all SQL statements that are executed by any JDBC client (including Hibernate, MyBatis, JdbcTemplate, native JDBC, etc.). Starting from jOOQ 3.18.0, 3.17.7, and 3.16.13, a LoggingConnection is now...

A frequently encountered doubt people have when using jOOQ is to decide when a “complex” query should be written using jOOQ API vs. when it should be implemented using native SQL. The jOOQ manual is full of side by side examples of the same query, e.g. Using jOOQ: Using native SQL: In the native SQL...

The standard SQL WITH clause has been tremendously helpful in structuring SQL queries. Instead of nesting everything in unreadable derived tables like this: People have started moving the logic up front, just like in any other programming language, where we declare things first, lexically, then use ...