Summary - Simple JOIN

Write a two-table report with INNER JOIN, ON and aliases.

Summary - Simple JOIN

In this group you learned JOIN, INNER JOIN, aliases, multi-table and WHERE filtering. You pull related data in one query.

SELECT o.id, c.name, p.name
FROM orders o
JOIN customers c ON o.customer_id = c.id
JOIN products p ON o.product_id = p.id
WHERE p.price > 10;

This query joins order, customer and product then filters pricey items.

o.id, c.name, p.name is selected from orders o. customers c is joined on o.customer_id = c.id, keeping only matching rows. products p is joined on o.product_id = p.id, keeping only matching rows. WHERE keeps only the rows where p.price > 10 holds.

Exercise Summary - Simple JOIN

Join orders and customers on customer_id = id; select id and name.

Show example solution

SELECT o.id, c.name
FROM orders o
JOIN customers c ON o.customer_id = c.id

Test yourself

Which rows does INNER JOIN return?
- Only the matching rows
- All rows
- The unmatched rows
- Empty ones
Show answer

Only the matching rows — INNER JOIN returns only matching rows.
Summary - Simple JOIN: match the terms

INNER JOIN

intersection
ON

condition
WHERE

filter
alias

short name

Next lesson: Inventory design

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