Three-State Booleans in Java
Every now and then, I miss SQL’s three-valued BOOLEAN semantics in Java. In SQL, we have: TRUE FALSE UNKNOWN (also known as NULL) Every now and then, I find myself in a situation where I wish I could...
View ArticleHow to Implement Sort Indirection in SQL
I’ve recently stumbled upon this interesting Stack Overflow question, where the user essentially wanted to ensure that resulting records are delivered in a well-defined order. They wrote...
View ArticleThe Index You’ve Added is Useless. Why?
Recently, at the office: Bob: I’ve looked into that slow query you’ve told me about yesterday, Alice. I’ve added the indexes you wanted. Everything should be fine now Alice: Thanks Bob. I’ll quickly...
View ArticleTime to break free from the SQL-92 mindset
Are you stuck in the 90s? If you are only using the SQL-92 language reference, then you are overlooking so many great features like: window functions MERGE TRUNCATE INSTEAD OF triggers Some test data...
View ArticleYet Another 10 Common Mistakes Java Developers Make When Writing SQL (You...
(Sorry for that click-bait heading. Couldn’t resist!) We’re on a mission. To teach you SQL. But mostly, we want to teach you how to appreciate SQL. You’ll love it! Getting SQL right or wrong shouldn’t...
View ArticleJava 8 Friday: JavaScript goes SQL with Nashorn and jOOQ
At Data Geekery, we love Java. And as we’re really into jOOQ’s fluent API and query DSL, we’re absolutely thrilled about what Java 8 will bring to our ecosystem. Java 8 Friday Every Friday, we’re...
View ArticleStop Trying to Emulate SQL OFFSET Pagination with Your In-House DB Framework!
I’m pretty sure you’ve gotten it wrong in numerous ways, so far. And you probably won’t get it right any time soon. So why waste your precious time on SQL tweaking, when you could be implementing...
View ArticleTracing SQL statements in JBoss AS 7 using a custom logging handler
Using an ORM to abstract from your specific database and to let it create and issue all the SQL statements you would have to write by hand yourself seems handy. This is what made ORM solutions popular....
View ArticleAre You Using SQL PIVOT Yet? You Should!
Every once in a while, we run into these rare SQL issues where we’d like to do something that seems out of the ordinary. One of these things is pivoting rows to columns. A recent question on Stack...
View ArticleSQL Tip of the Day: Be Wary of SELECT COUNT(*)
Recently, I’ve encountered this sort of query all over the place at a customer site: DECLARE v_var NUMBER(10); BEGIN SELECT COUNT(*) INTO v_var FROM table1 JOIN table2 ON...
View ArticleAll You Ever Need to Know About Recursive SQL
Oracle SYNONYMs are a great feature. You can implement all sorts of backwards-compatibility tweaks simply by creating SYNONYMs in your database. Consider the following schema: CREATE...
View ArticleA Wonderful SQL Feature: Quantified Comparison Predicates (ANY, ALL)
Have you ever wondered about the use-case behind SQL’s ANY (also: SOME) and ALL keywords? You have probably not yet encountered these keywords in the wild. Yet they can be extremely useful. But first,...
View ArticleAwesome SQL Trick: Constraints on Views
CHECK constraints are already pretty great when you want to sanitize your data. But there are some limitations to CHECK constraints, including the fact that they are applied to the table itself, when...
View ArticleAsynchronous SQL Execution with jOOQ and Java 8’s CompletableFuture
Reactive programming is the new buzzword, which essentially just means asynchronous programming or messaging. Fact is that functional syntax greatly helps with structuring asynchronous execution...
View ArticleDon’t Miss out on Writing Java 8 SQL One-Liners with jOOλ or jOOQ
More and more people are catching up with the latest update to our platform by adopting functional programming also for their businesses. At Data Geekery, we’re using Java 8 for our jOOQ integration...
View ArticleAn entity modelling strategy for scaling optimistic locking
Introduction Application-level repeatable reads are suitable for preventing lost updates in web conversations. Enabling entity-level optimistic locking is fairly easy. You just have to mark one...
View ArticleHave You Ever Wondered About the Difference Between NOT NULL and DEFAULT?
When writing DDL in SQL, you can specify a couple of constraints on columns, like NOT NULL or DEFAULT constraints. Some people might wonder, if the two constraints are actually redundant, i.e. is it...
View ArticlePainless Access from Java to PL/SQL Procedures with jOOQ
PL/SQL is one of those things. Most people try to stay clear of it. Few people really love it. I just happen to suffer from stockholm syndrome, since I’m working a lot with banks. Even if the PL/SQL...
View ArticleDon’t Miss out on Awesome SQL Power with FIRST_VALUE(), LAST_VALUE(), LEAD(),...
If you’re using a commercial database or PostgreSQL / Firebird / CUBRID, you will be able to take advantage of the full power of window functions. We’ve blogged about window functions’ awesomeness a...
View ArticleThe downside of version-less optimistic locking
Introduction In my previous post I demonstrated how you can scale optimistic locking through write-concerns splitting. Version-less optimistic locking is one lesser-known Hibernate feature. In this...
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