What SQL Is, and Where to Start
SQL is the language you use to ask a database for exactly the data you want.
Total up sales, count the customers who match a condition, pull two tables together into one view. Work you would otherwise do by hand in a spreadsheet becomes a single query.
Reading about it does not stick. Every screen on this page is driven by a real database, so you see the result first and then type the same thing yourself.
What learning SQL gets you
Get the numbers yourself
Instead of asking someone for "last month by customer" and waiting, you write the query and have it in minutes.
Read the shape of data
Once tables, rows, columns, and keys click, you can read an unfamiliar system from its structure.
Join what is scattered
Orders here, customers there. Match them on a key and pull them out as one table.
Try a real lesson, right here
What order to learn in
One course for now. Ten lessons, from connecting to a database through rewriting rows.
Almost no prerequisites
Ask the Data Yourself
SQL Introduction
Filter, summarize, and join
Open the real psql prompt in your browser. Get the numbers you need without waiting on anyone.
Connect, look at a table, filter, summarize, and join. It ends with updates and rolling them back. That covers the queries most day-to-day reporting needs.