Real Project: Multi-Table Reporting Query

Congratulations! You've finished **Phase 3**. You've mastered the most difficult structural concept in SQL.

Today, we're building a "Full Customer Snapshot" report.

The Requirement

The Marketing VP wants a report that shows:

The Multi-Table Solution

SELECT

c.name,

SUM(o.total_price) AS lifetime_spend,

MIN(o.order_date) AS first_order,

am.manager_name

FROM customers c

LEFT JOIN orders o ON c.id = o.customer_id

LEFT JOIN account_managers am ON c.manager_id = am.id

GROUP BY c.name, am.manager_name

ORDER BY lifetime_spend DESC;

Why we used LEFT JOIN

We want to see *all* customers, even if they haven't been assigned a manager yet or haven't made an order. Using an `INNER JOIN` here would hide potential new customers!

What's Next?

You can now connect the whole database together. In **Phase 4 (Days 46–60)**, we'll learn how to write "Queries within Queries" (**Subqueries**) and use **CTEs** to make your code look senior and professional.

See you in Phase 4!