Table redesign

Rebuild a table with DROP and CREATE.

Challenge 4: Join tables

In this challenge you will write a query that joins two tables and filters the result.

SELECT o.id, c.name FROM orders o JOIN customers c ON o.customer_id = c.id WHERE c.city = 'İstanbul';

This query returns orders from Istanbul customers.

o.id, c.name is selected from orders o. customers c is joined on o.customer_id = c.id, keeping only matching rows. WHERE keeps only the rows where c.city = 'İstanbul' holds.

Exercise Challenge 4: Join tables

JOIN orders and customers on customer_id = id; return only Istanbul customers.

Show example solution

SELECT o.id, c.name
FROM orders o
JOIN customers c ON o.customer_id = c.id
WHERE c.city = 'İstanbul'

Test yourself

Join and filter

SELECT o.id, c.name
FROM orders o
JOIN customers c ON o.customer_id = c.id
____ c.city = 'İstanbul';

Show answer

SELECT o.id, c.name
FROM orders o
JOIN customers c ON o.customer_id = c.id
WHERE c.city = 'İstanbul';

Where does the JOIN condition go?
- WHERE
- ON
- FROM
- GROUP BY
Show answer

ON — The JOIN condition goes in ON.

Next lesson: Beginner section exam

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