FAQ: Multiple Tables - Review


#1

This community-built FAQ covers the “Review” exercise from the lesson “Multiple Tables”.

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#2

I’ve build up some tables and I’m happy with my result and I want to share it! I’m just a beginner of programming and thx for the courses I really learnt a lot!!

– Table 1

WITH report_1 AS(

WITH report AS(
SELECT customer_id, subscription_id, COUNT(subscription_id) AS ‘quantity’
FROM orders
GROUP BY 1,2)

SELECT report.customer_id, subscriptions.description, report.quantity
FROM subscriptions
JOIN report
ON subscriptions.subscription_id = report.subscription_id)

SELECT customers.customer_id AS ‘ID’, customers.customer_name AS ‘Customer Name’, report_1.description AS ‘Magazine’, report_1.quantity AS ‘Quantity’
FROM customers
JOIN report_1
ON report_1.customer_id = customers.customer_id
ORDER BY 1;

– Table 2 (Short Form)

WITH report_1 AS(

WITH report AS(
SELECT customer_id, subscription_id, COUNT(subscription_id) AS ‘quantity’
FROM orders
GROUP BY 1,2)

SELECT report.customer_id, subscriptions.description, report.quantity
FROM subscriptions
JOIN report
ON subscriptions.subscription_id = report.subscription_id)

SELECT customers.customer_id AS ‘ID’,

CASE
WHEN report_1.description LIKE ‘%Politics%’ THEN ‘P’
WHEN report_1.description LIKE ‘%Sports%’ THEN ‘S’
WHEN report_1.description LIKE ‘%Fashion%’ THEN ‘F’
ELSE NULL
END AS ‘Magazine’,

report_1.quantity AS ‘Quantity’
FROM customers
JOIN report_1
ON report_1.customer_id = customers.customer_id
ORDER BY 1;

– Table 3 (for purchasing easy reference)

SELECT Magazine, COUNT(*)

FROM(

WITH report_1 AS(

WITH report AS(
SELECT customer_id, subscription_id, COUNT(subscription_id) AS ‘quantity’
FROM orders
GROUP BY 1,2)

SELECT report.customer_id, subscriptions.description, report.quantity
FROM subscriptions
JOIN report
ON subscriptions.subscription_id = report.subscription_id)

SELECT customers.customer_id AS ‘ID’,

CASE
WHEN report_1.description LIKE ‘%Politics%’ THEN ‘P’
WHEN report_1.description LIKE ‘%Sports%’ THEN ‘S’
WHEN report_1.description LIKE ‘%Fashion%’ THEN ‘F’
ELSE NULL
END AS ‘Magazine’,

report_1.quantity AS ‘Quantity’
FROM customers
JOIN report_1
ON report_1.customer_id = customers.customer_id
ORDER BY 1)

GROUP BY Magazine
ORDER BY 2;