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Sample exercise preview

Exercise Console · SQL Database

Beginner

Laboratory Task

SQL Multi-Table Joins & Order Aggregation

Write relational queries with INNER JOIN, LEFT JOIN, GROUP BY, and HAVING to generate customer purchase summaries.

Execution Steps:

01.Inspect the relational schema for customers, orders, and line items.

02.Construct an INNER JOIN between customers and orders.

03.Group by customer ID and calculate total order count and aggregate expenditure.

04.Filter for customers with total spend exceeding 5,000 using HAVING.

Sample Script SourceRead-Only

SELECT
  c.customer_id,
  c.first_name || ' ' || c.last_name AS customer_name,
  COUNT(o.order_id) AS total_orders,
  ROUND(SUM(o.total_amount)::numeric, 2) AS lifetime_spend
FROM customers c
INNER JOIN orders o ON c.customer_id = o.customer_id
WHERE o.status = 'COMPLETED'
GROUP BY c.customer_id, c.first_name, c.last_name
HAVING SUM(o.total_amount) > 5000
ORDER BY lifetime_spend DESC;

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