Writing Tests for Data Access Code – Don’t Forget the Database

When we write tests for our data access code, we must follow these three rules:          …

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PostgreSQL’s Table-Valued Functions

Table-valued functions are an awesome thing. Many databases support them in one way or another and so does PostgreSQL. In…

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Flyway and jOOQ for Unbeatable SQL Development Productivity

When performing database migrations, we at Data Geekery recommend using jOOQ with Flyway – Database Migrations Made Easy. In this…

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Database primary key flavors

Types of primary keys All database tables must have one primary key column. The primary key uniquely identifies a row…

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MySQL error: Can’t connect to MySQL server

You may have stumbled on this MySQL error. If you have already seen this before, then it’s really easy to…

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

(Sorry for that click-bait heading. Couldn’t resist!) We’re on a mission. To teach you SQL. But mostly, we want to…

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MySQL Transaction Isolation Levels and Locks

Recently, an application that my team was working on encountered problems with a MySQL deadlock situation and it took us…

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Seven Databases in Seven Weeks – Hbase Day 2

This post is a recap of the second day of Hbase from the Seven Databases in Seven Weeks book. Most…

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SQL Server Trick: Circumvent Missing ORDER BY Clause

SQL Server is known to have a very strict interpretation of the SQL standard. For instance, the following expressions or…

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