Emulating SQL FILTER with Oracle JSON Aggregate Functions
JOOQ
by lukaseder
6M ago
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 computed in one go. For most basic types ..read more
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Getting Top 1 Values Per Group in Oracle
JOOQ
by lukaseder
10M ago
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 ..read more
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An Efficient Way to Check for Existence of Multiple Values in SQL
JOOQ
by lukaseder
10M ago
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 ..read more
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A Hidden Benefit of Implicit Joins: Join Elimination
JOOQ
by lukaseder
1y ago
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 feature ..read more
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JOOQ 3.19’s new Explicit and Implicit to-many path joins
JOOQ
by lukaseder
1y ago
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 path join is a join derived from ..read more
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Workaround for MySQL’s “can’t specify target table for update in FROM clause” Error
JOOQ
by lukaseder
1y ago
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 clones ..read more
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JOOQ 3.19.0 Released with DuckDB, Trino, Oracle 23c support, join path improvements, an official gradle plugin, commercial maven repositories, policies, UDT paths, trigger meta data, hierarchies, and much more
JOOQ
by lukaseder
1y ago
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, big new CockroachDB and Oracle versions have shipped ..read more
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Maven Coordinates of the most popular JDBC Drivers
JOOQ
by lukaseder
1y ago
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 database and driver: https://central.sonatype.com/search?q=g%3Acom.h2database+a%3Ah2 The list only includes drivers ..read more
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To DAO or not to DAO
JOOQ
by lukaseder
1y ago
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 individual queries much thought. A fun ..read more
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JDBC Connection URLs of the Most Popular RDBMS
JOOQ
by lukaseder
1y ago
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 ..read more
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