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Author Archives: Lukas Eder

Lukas is a Java and SQL enthusiast developer. He created the Data Geekery GmbH. He is the creator of jOOQ, a comprehensive SQL library for Java, and he is blogging mostly about these three topics: Java, SQL and jOOQ.

The “Free”, “Standard”, “Open” Software Heresy

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There are those people that have a strong, dogmatic belief in what they call “Free” or “Standard” or “Open” software. One of those individuals is Jimmie (let’s call him Jimmie in this article) who has responded to an article about Java persistence by Marco Behler on TheServerSide. Let me cite Jimmie’s response here:           JPA is ...

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SQL Tip of the Day: Be Wary of SELECT COUNT(*)

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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 table1.t1_id = table2.t1_id JOIN table3 ON table2.t2_id = table3.t2_id ... WHERE some_predicate; IF (v_var = 1) THEN do_something ELSE do_something_else END IF; ...

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Are You Using SQL PIVOT Yet? You Should!

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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 Overflow by Valiante asked for precisely this. Going from this table:             +------+------------+----------------+-------------------+ | dnId | propNameId ...

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Top 10 Very Very VERY Important Topics to Discuss

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Some things are just very very very VERY very important. Such as John Cleese. The same is true for Whitespace:                 Yes. 1080 Reddit Karma points (so urgently needed!) in only 23 hours. That’s several orders of magnitudes better than any of our – what we wrongfully thought to be – very deep ...

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Using Oracle AQ in Java Won’t Get Any Easier Than This

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As recently announced in our newsletter, the upcoming jOOQ 3.5 will include an awesome new feature for those of you using the Oracle database: Native support for Oracle AQ! And your client code will be so easy to write, you’ll be putting those AQs all over your database immediately. How does it work? jOOQ rationale The biggest reason why many ...

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Keeping things DRY: Method overloading

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A good clean application design requires discipline in keeping things DRY: Everything has to be done once. Having to do it twice is a coincidence. Having to do it three times is a pattern. — An unknown wise man Now, if you’re following the Xtreme Programming rules, you know what needs to be done, when you encounter a pattern: refactor ...

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Java 8 Friday: More Functional Relational Transformation

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In the past, we’ve been providing you with a new article every Friday about what’s new in Java 8. It has been a very exciting blog series, but we would like to focus again more on our core content, which is Java and SQL. We will still be occasionally blogging about Java 8, but no longer every Friday (as some ...

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PostgreSQL’s Table-Valued Functions

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Table-valued functions are an awesome thing. Many databases support them in one way or another and so does PostgreSQL. In PostgreSQL, (almost) everything is a table. For instance, we can write:                 CREATE OR REPLACE FUNCTION f_1 (v1 INTEGER, v2 OUT INTEGER) AS $$ BEGIN v2 := v1; END $$ LANGUAGE plpgsql; … ...

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Flyway and jOOQ for Unbeatable SQL Development Productivity

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When performing database migrations, we at Data Geekery recommend using jOOQ with Flyway – Database Migrations Made Easy. In this post, we’re going to look into a simple way to get started with the two frameworks.     Philosophy There are a variety of ways how jOOQ and Flyway could interact with each other in various development setups. In this ...

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