Exam DA0-001 topic 1 question 76 discussion

Actual exam question from CompTIA's DA0-001

Question #: 76
Topic #: 1

A data analyst has been asked to merge the tables below, first performing an INNER JOIN and then a LEFT JOIN:

Customer Table -

In-store Transactions -

Which of the following describes the number of rows of data that can be expected after performing both joins in the order stated, considering the customer table as the main table?

A. INNER: 6 rows; LEFT: 9 rows
B. INNER: 9 rows; LEFT: 6 rows
C. INNER: 9 rows; LEFT: 15 rows
D. INNER: 15 rows; LEFT: 9 rows

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Suggested Answer: D 🗳️

by Hiromi_Nakatani at Feb. 4, 2023, 4:33 p.m.

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willsy

9 months ago

A - INNER joins the ones with the same in both, there are only 6. A

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ronniehaang

1 year, 3 months ago

A. INNER: 6 rows; LEFT: 9 rows Explanation: INNER JOIN: An INNER JOIN returns only the rows that match in both tables. The common column used for joining is "Customer ID". In this case, there are 6 customers with matching Customer IDs in both the Customer Table and In-store Transactions table, so the number of rows after performing an INNER JOIN would be 6. LEFT JOIN: A LEFT JOIN returns all the rows from the left table (Customer Table), and the matching rows from the right table (In-store Transactions). If there is no match, NULL values will be displayed in the right table columns. In this case, there are 9 customers in the Customer Table, but only 6 have matching Customer IDs in the In-store Transactions table, so there would be 9 rows after performing a LEFT JOIN.

upvoted 3 times

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Hiromi_Nakatani

1 year, 3 months ago

Selected Answer: A

A. INNER: 6 rows; LEFT: 9 rows

upvoted 2 times

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Exam DA0-001 topic 1 question 76 discussion

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