Home » Author Archives: Lukas Eder (page 12)

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.

Yet Another 10 Common Mistakes Java Developers Make When Writing SQL (You Won’t BELIEVE the Last One)

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(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 be about that You’re-Doing-It-Wrong™ attitude that can be encountered often when evangelists promote their object of evangelism. Getting SQL right should be about the fun ...

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Java 8 Friday: Better Exceptions

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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 showing you a couple of nice new tutorial-style Java 8 features, which take advantage of lambda expressions, extension methods, and other great stuff. You’ll find ...

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Free as in Beer has caused Heartbleed (and Much More)

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Heartbleed is a bit over one month old now. A bug significant enough to have its own Wikipedia page. Today, we’re going to look into how wrong we have been in assuming that Open Source software is more secure than commercial software, because of our thinking that source code is open and that many developers are looking into it.   ...

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Java 8 Friday: API Designers, be Careful

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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 showing you a couple of nice new tutorial-style Java 8 features, which take advantage of lambda expressions, extension methods, and other great stuff. You’ll find ...

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SQL Server Trick: Circumvent Missing ORDER BY Clause

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SQL Server is known to have a very strict interpretation of the SQL standard. For instance, the following expressions or statements are not possible in SQL Server:                   -- Get arbitrarily numbered row_numbers SELECT ROW_NUMBER() OVER () -- Skip arbitrary rows SELECT a FROM (VALUES (1), (2), (3), (4)) t(a) OFFSET 3 ...

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The Index You’ve Added is Useless. Why?

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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 check … Nope Bob, still slow, it didn’t seem to work Bob: You’re right Alice! It looks like Oracle isn’t picking up the index, for your query ...

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Java 8 Friday: Language Design is Subtle

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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 showing you a couple of nice new tutorial-style Java 8 features, which take advantage of lambda expressions, extension methods, and other great stuff. You’ll find ...

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How to Implement Sort Indirection in SQL

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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             SELECT name FROM product WHERE name IN ('CE367FAACDHCANPH-151556', 'CE367FAACEX9ANPH-153877', 'NI564FAACJSFANPH-162605', 'GE526OTACCD3ANPH-149839') They got CE367FAACDHCANPH-151556 CE367FAACEX9ANPH-153877 GE526OTACCD3ANPH-149839 NI564FAACJSFANPH-162605 They wanted CE367FAACDHCANPH-151556 CE367FAACEX9ANPH-153877 NI564FAACJSFANPH-162605 GE526OTACCD3ANPH-149839 Very often, according to ...

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Three-State Booleans in Java

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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 also express this UNKNOWN or UNINITIALISED semantics in Java, when plain true and false aren’t enough.   Implementing a ResultSetIterator For instance, ...

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Java 8 Friday: Let’s Deprecate Those Legacy Libs

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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 showing you a couple of nice new tutorial-style Java 8 features, which take advantage of lambda expressions, extension methods, and other great stuff. You’ll find ...

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