This is an extension to PostgreSQL vs MySQL: How to UPDATE using a JOIN. UPDATE employees SET department_name = departments.name...
Slides for Henning's talk on Sep 21st 2017. Understanding sync vs. async control flow Talking to synchronous (or "blocking...
When using GROUP BY, MySQL now complains if the SELECT includes columns which are not part of the GROUP BY...
This card compares patterns to store trees in a relation database like MySQL or PostgreSQL. Implementation examples are for the...
Barby is a great Ruby gem to generate barcodes of all different sorts. It includes support for QR codes via...
on the bash (issued as postgres user) Start/Stop/Restart PostgreSQL pg_ctl -D $configdir start|stop|restart Start/Stop/Restart the corresponding PostgreSQL...
If you have a replication error with MySQL and you know the "error" is okay (e.g. you've executed the...
Exercise 1: XML On the start page of your Movie DB, show the title of a random movie that is...
When working with custom transactions and use ActiveRecord::Rollback you may encounter unexpected behaviour if you try to roll back...
SVG is an acronym for "scalable vector graphics". SVGs should be used whenever an image can be described with vector...
We have released a new library Gemika to help test a gem against multiple versions of Ruby, gem dependencies and...
We have a new gem Minidusen which extracts Dusen's query parsing and LIKE query functionality. Minidusen can no longer...
If you were using Dusen for its query parsing and LIKE queries, we recommend to migrate to Minidusen, which extracts...
Sometimes you want to test migrations with production or staging data. Dumping single tables makes sense if a complete dump...
PostgreSQL, unlike MySQL, treats strings as case sensitive in all circumstances. This includes comparison with = and LIKE collision detection in...
Apparently you can pash a second scope to a hash-condition and the whole thing will be evaluated as a...
If you have made any changes to a libvirt xml config file you have to reload is. One way is...
Spreewald gives you the within meta step that will constrain page inspection to a given scope. Unfortunately, this does not...
ActiveRecord offers an explain method similar to using EXPLAIN SQL statements on the database. However, this approach will explain all...
Instead of using this hack you might want to use MariaDB 10.x which can work with both old and...
You can find out about disk space usage of all tables within your database by running this: SELECT table_name...
If you want to perform a failover on another haproxy backend server this is the way you should do it...
SELECT pg_database.datname as "database_name", pg_database_size(pg_database.datname)/1024/1024 AS size_in_mb FROM pg_database ORDER...
If you have many connections to your MySQL or MariaDB (as we have) you might want to filter the list...