[Solved] You want to list all customers who bought either pr... Tables:ProductA_Customers: customer_idProductB_Customers: customer_idWhich query correctly lists all unique customers who bought either product? | SQL

SQL - Set Operations

You want to list all customers who bought either product A or product B. Tables:
ProductA_Customers: customer_id
ProductB_Customers: customer_id
Which query correctly lists all unique customers who bought either product?

ASELECT customer_id FROM ProductA_Customers UNION SELECT customer_id FROM ProductB_Customers;

BSELECT customer_id FROM ProductA_Customers UNION ALL SELECT customer_id FROM ProductB_Customers;

CSELECT DISTINCT customer_id FROM ProductA_Customers JOIN ProductB_Customers;

DSELECT customer_id FROM ProductA_Customers INTERSECT SELECT customer_id FROM ProductB_Customers;

Step-by-Step Solution

Solution:

Step 1: Understand requirement for unique customers
We want all customers who bought either product, no duplicates.
Step 2: Use UNION to combine and remove duplicates
UNION combines both lists and removes duplicates.
Step 3: Check other options
UNION ALL keeps duplicates; JOIN lists only customers who bought both; INTERSECT lists common customers only.
Final Answer:
SELECT customer_id FROM ProductA_Customers UNION SELECT customer_id FROM ProductB_Customers; -> Option A
Quick Check:
UNION for unique combined list = B [OK]

Quick Trick: Use UNION to get unique combined customer list [OK]

Common Mistakes:

MISTAKES

Using UNION ALL causing duplicates
Using JOIN or INTERSECT instead of UNION
Not removing duplicates

Master "Set Operations" in SQL

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More SQL Quizzes

You want to list all customers who bought either product A or product B. Tables:

Step 1: Understand requirement for unique customers

Step 2: Use UNION to combine and remove duplicates

Step 3: Check other options

Final Answer:

Quick Check:

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