IBM PureData System for Analytics V7.0 — Question 1

You have two data sets. One data set contains customer name and age information along with a customer ID. The second data set contains the customer ID along with address information. There are no addresses which do not belong to a customer, there are customers which have no address, and there are customers which have multiple addresses.
Which type of join will display all customers who have no recorded address?

Answer options

• A. Inner join
• B. Outer join
• C. Partial outer join
• D. Anti-join

Correct answer: C

Explanation

A Partial outer join will return all records from one dataset and only the matching records from the other, making it suitable for identifying customers without addresses. An Inner join would exclude customers without addresses, while an Outer join would list all customers with and without addresses, not specifically highlighting those without. An Anti-join, while useful for showing unmatched records, is not a standard term in SQL and might not be recognized in all contexts.