Everything we did in the last articles of the series SQL-Tutorial was a dry run because we just used SQLFiddle. So let’s start with a real database like SQLite. SQLite is a file based DBRMS and can be used for e.g. web sites. The official docs say: “SQLite works great as the database engine for…
This article is part of my SQL-Tutorial Motivation Sometimes you need to retrieve data from a database without knowing the exact string to look up so wildcards for the rescue Underscore Se_en represents a pattern with a wildcard character. The _ means you can substitute any individual character here without breaking the pattern. It matches…
As the Junior Data Scientist of Knight Industries we created a table to keep track of all our operatives: SQL-Basics: Create, Read, Update, Delete Devon asks us to keep track of our operations aka missions as well. For the first implementation let us assume that a mission has one operative and an operative can participate…
This episode is about the basic statements needed to create, read, update and delete data in a database system. It is part of my SQL-Tutorial Motivation Let’s assume we work as a data scientist for Knight Industries. We want to help the Foundation of Law and Government to keep track of our operatives. We decide…
Sometimes You screw up your database design and you have redundancies i.e. your database is not normalized. If You want to correct that: Subqueries for the rescue! In our example we have two tables which contain almost the same information: CREATE TABLE installed_device (`id` int, `device` text, `info` text); INSERT INTO installed_device (`id`, `device`, `info`)…