SQL is the language you use to talk to a relational database, and it is the tool a database administrator reaches for every day. SQL & query writing turns the tables and keys from the last module into something you can actually work with: asking questions of your data, and changing it safely.
You'll start with the basics of SELECT queries, then learn to filter and sort results with WHERE, ORDER BY, and wildcards. From there the module covers joins for combining tables, aggregate functions with GROUP BY, and subqueries, along with the statements that create tables and insert, update, and delete data. The lessons use MySQL and PostgreSQL, so you'll see how the same SQL works across different database systems.
Once you can write queries confidently, you'll be ready for the next module, Installation & Configuration, where you set up and configure database servers yourself.
A quick introduction to SQL that covers creating tables, inserting data, primary and foreign keys, and aggregate functions. A good first look before the longer courses.
A hands-on MySQL walkthrough covering creating and altering tables, inserting data, keys, and aggregate functions, with a cheat sheet to keep for reference.
Set up PostgreSQL on Mac or Windows, then learn the SQL basics: creating tables, keys, and aggregate functions. Useful for seeing SQL on a second database system.
A structured course on writing queries in MySQL, including inserting data, joins, SQL operators, and clauses, with plenty of practice examples.
A complete beginner course that goes from basic queries to wildcards, unions, joins, nested queries, and triggers, building a company database along the way.