JOIN Questions Part I

 

JOIN Questions Part I


Question Mania


Now that you have been introduced to JOINs, let's practice to build your skills and comfort with this new tool. Below I have provided the ERD and a bunch of questions. The solutions for the questions can be found on the next concept for you to check your answers or just in case you get stuck!

I recommend testing your queries with the environment below, and then saving them to a file. Then compare your file to my solutions on the next concept!


Questions and Solutions


  1. Provide a table for all the for all web_events associated with account name of Walmart. There should be three columns. Be sure to include the primary_poc, time of the event, and the channel for each event. Additionally, you might choose to add a fourth column to assure only Walmart events were chosen.

SELECT a.primary_poc, w.occurred_at, w.channel, a.name
FROM web_events w
JOIN accounts a
ON w.account_id = a.id
WHERE a.name = 'Walmart';
  1. Provide a table that provides the region for each sales_rep along with their associated accounts. Your final table should include three columns: the region name, the sales rep name, and the account name. Sort the accounts alphabetically (A-Z) according to account name.
SELECT r.name region, s.name rep, a.name account
FROM sales_reps s
JOIN region r
ON s.region_id = r.id
JOIN accounts a
ON a.sales_rep_id = s.id
ORDER BY a.name;
  1. Provide the name for each region for every order, as well as the account name and the unit price they paid (total_amt_usd/total) for the order. Your final table should have 3 columns: region name, account name, and unit price. A few accounts have 0 for total, so I divided by (total + 0.01) to assure not dividing by zero.
SELECT r.name region, a.name account, 
           o.total_amt_usd/(o.total + 0.01) unit_price
FROM region r
JOIN sales_reps s
ON s.region_id = r.id
JOIN accounts a
ON a.sales_rep_id = s.id
JOIN orders o
ON o.account_id = a.id;

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