Unleashing the Power of Join Queries with Subqueries: A Mind-Opening Journey
Are you ready to elevate your SQL skills and embark on a mind-opening exploration of join queries with subqueries? Buckle up as we unravel the intricacies of a powerful query that delves into the sales realm, providing insights that will transform the way you approach database challenges.
SCHEMA :
Query: Provide the name of the sales rep in each region with the largest amount of total_amt_usd sales.
Solution:
SELECT all_region_sales.sales_rep, all_region_sales.region, all_region_sales.total_amt
FROM
(SELECT region, MAX(total_amt) AS max_amt
FROM
(SELECT s.name AS sales_rep, r.name AS region, SUM(total_amt_usd) AS total_amt
FROM orders o
INNER JOIN accounts a ON o.account_id = a.id
INNER JOIN sales_reps s ON a.sales_rep_id = s.id
INNER JOIN region r ON r.id = s.region_id
GROUP BY s.name, r.name) AS all_orders
GROUP BY region) AS regions_sales
JOIN
(SELECT s.name AS sales_rep, r.name AS region, SUM(total_amt_usd) AS total_amt
FROM orders o
INNER JOIN accounts a ON o.account_id = a.id
INNER JOIN sales_reps s ON a.sales_rep_id = s.id
INNER JOIN region r ON r.id = s.region_id
GROUP BY s.name, r.name) AS all_region_sales
ON regions_sales.region = all_region_sales.region AND regions_sales.max_amt = all_region_sales.total_amt;
Dive into the Query’s Brilliance:
- Nested Aggregation: The query employs nested aggregation to identify the maximum total_amt for each region, creating a foundation for precise analysis.
- Strategic Joins: Leveraging INNER JOINs, the query seamlessly connects orders, accounts, sales reps, and regions, creating a comprehensive view of the sales landscape.
- Mindful Grouping: Through strategic GROUP BY clauses, the query efficiently organizes and aggregates data, ensuring accurate results and optimal performance.
Optimizing the Query:
Your journey doesn’t end here! Explore optimization opportunities and alternative approaches to fine-tune this query further. Your suggestions and insights are invaluable — let’s collectively refine and enhance this query to unlock its full potential.
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Together, we’ll navigate the complexities of SQL and elevate our skills.
All the best and Happy learning!
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