Table Joins

Use orders.db to complete the following queries:

orders.db

joins1.sql

SELECT *
FROM menu JOIN orders ON menu.title == orders.title

joins2.sql

SELECT orders.customer_name, SUM(menu.price*orders.quantity) AS "Amount owing"
FROM menu JOIN orders ON menu.title == orders.title
GROUP BY orders.customer_name

joins3.sql

SELECT orders.customer_name, menu.category
FROM orders LEFT JOIN menu ON menu.title == orders.title

The default join in SQLite is an inner join. When you use the keyword JOIN, you can interchange this with INNER JOIN as this is what the word JOIN defaults to:



The bottom SQL join example (above) shows a LEFT join in action:



Note the table on the left of the LEFT is all inclusive of records, in addition to the equal records to the table on the right.

You are welcome to research other types of joins at your leisure (such as cross joins for example). It is likely though that the above joins will be all you will need for your studies to date.