Solution:Step 1: Understand FULL OUTER JOIN with WHERE filterThe join returns all customers and orders; filtering WHERE Orders.OrderID IS NULL keeps rows where no matching order exists.Step 2: Interpret the filter effectRows with NULL in Orders.OrderID mean customers without orders are selected.Fina

[Solved] Consider this query:SELECT * FROM Customers FULL OUTER JOIN Orders ON Customers.CustomerID = Orders.CustomerID WHERE Orders.OrderID IS NULL;What is the likely purpose of this query? | SQL

SQL - Advanced Joins

Consider this query:

SELECT * FROM Customers FULL OUTER JOIN Orders ON Customers.CustomerID = Orders.CustomerID WHERE Orders.OrderID IS NULL;

What is the likely purpose of this query?

ATo find orders without customers.

BTo find customers who have no orders.

CTo find all customers and orders regardless of match.

DTo find customers with at least one order.

Step-by-Step Solution

Solution:

Step 1: Understand FULL OUTER JOIN with WHERE filter
The join returns all customers and orders; filtering WHERE Orders.OrderID IS NULL keeps rows where no matching order exists.
Step 2: Interpret the filter effect
Rows with NULL in Orders.OrderID mean customers without orders are selected.
Final Answer:
To find customers who have no orders. -> Option B
Quick Check:
Filter NULL in Orders = customers without orders [OK]

Quick Trick: Filter NULL in joined table to find unmatched rows [OK]

Common Mistakes:

MISTAKES

Thinking it finds orders without customers
Assuming it returns all rows without filtering
Confusing NULL filter with matching rows

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Consider this query:

Step 1: Understand FULL OUTER JOIN with WHERE filter

Step 2: Interpret the filter effect

Final Answer:

Quick Check:

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