[Solved] You want to delete a customer from Customers table who has orders in Orders table.... What will happen when you delete that customer? | SQL

SQL - Table Constraints

You want to delete a customer from Customers table who has orders in Orders table. The Orders table has a FOREIGN KEY on CustomerID referencing Customers(CustomerID) with ON DELETE CASCADE. What will happen when you delete that customer?

AThe delete fails because orders exist for that customer

BThe customer is deleted and all their orders are automatically deleted

CThe customer is deleted but orders remain with invalid CustomerID

DThe delete succeeds but sets CustomerID in orders to NULL

Step-by-Step Solution

Solution:

Step 1: Understand ON DELETE CASCADE effect
ON DELETE CASCADE means deleting a parent row also deletes all related child rows automatically.
Step 2: Apply to deleting a customer with orders
Deleting the customer will also delete all orders linked by CustomerID in Orders table.
Final Answer:
The customer is deleted and all their orders are automatically deleted -> Option B
Quick Check:
ON DELETE CASCADE deletes related rows [OK]

Quick Trick: ON DELETE CASCADE removes child rows with parent [OK]

Common Mistakes:

MISTAKES

Assuming delete fails due to existing child rows
Thinking child rows remain with broken references
Confusing CASCADE with SET NULL behavior

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More SQL Quizzes

What will happen when you delete that customer?

Step 1: Understand ON DELETE CASCADE effect

Step 2: Apply to deleting a customer with orders

Final Answer:

Quick Check:

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