SQL and databases

Tables, rows and columns, and a language for asking them.

Try:

The answer

The database

Click a table to look inside it. 🔑 marks the primary key.

Run so far

The database is built again from these every time; nothing is saved.

The parts of a query

SELECT … FROM: which columns, from which table.
WHERE: which rows.
JOIN … ON: put tables together through their keys.
GROUP BY and COUNT, AVG, SUM: one row per group.
HAVING: which groups.
ORDER BY and LIMIT: in which order, and how many.
INSERT, UPDATE and DELETE: change the rows. Without a WHERE, UPDATE and DELETE touch every row.