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…
Sometimes your RDBMS does not allow you to do certain changes like updating a table without using a WHERE clause that uses a key column. When you are really sure what you want to do: SET SQL_SAFE_UPDATES = 0; Now the dirty brown magic can begin! Back to the SQL-Tutorial
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`)…