The Performance Impact of SQL’s FILTER Clause
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...
View ArticleHow to Write a Derived Table in jOOQ
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...
View ArticleHow to use jOOQ’s Converters with UNION Operations
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...
View Article3.18.0 Release with Support for more Diagnostics, SQL/JSON, Oracle...
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...
View ArticleHow to Turn a List of Flat Elements into a Hierarchy in Java, SQL, or jOOQ
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 | |---|---------|-------------------|...
View ArticleHow to Pass a Table Valued Parameter to a T-SQL Function with jOOQ
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:...
View ArticleHow to Generate Package Private Code with jOOQ’s Code Generator
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...
View ArticleJDBC Connection URLs of the Most Popular RDBMS
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:
View ArticleTo DAO or not to DAO
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...
View ArticleMaven Coordinates of the most popular JDBC Drivers
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...
View ArticlejOOQ 3.19.0 Released with DuckDB, Trino, Oracle 23c support, join path...
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...
View ArticleWorkaround for MySQL’s “can’t specify target table for update in FROM clause”...
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...
View ArticlejOOQ 3.19’s new Explicit and Implicit to-many path joins
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,...
View ArticleA Hidden Benefit of Implicit Joins: Join Elimination
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....
View ArticleAn Efficient Way to Check for Existence of Multiple Values in SQL
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...
View ArticleGetting Top 1 Values Per Group in Oracle
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...
View ArticleEmulating SQL FILTER with Oracle JSON Aggregate Functions
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...
View ArticlejOOQ 3.20 released with ClickHouse, Databricks, and much more DuckDB support,...
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...
View ArticleResisting the Urge to Document Everything Everywhere
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...
View ArticleThink About SQL MERGE in Terms of a RIGHT JOIN
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...
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