Quick Answer
The answer is DISTINCTCOUNT(Sales[ProductID]) because this DAX function is specifically designed to count unique values in a column, making it the correct choice for a distinct count of products sold. Unlike COUNT, which tallies only numeric non-blank cells, or COUNTA, which counts any non-blank value regardless of data type, DISTINCTCOUNT ignores duplicates and returns the exact number of distinct ProductID entries in the Sales table. On the Microsoft Power BI Data Analyst PL-300 exam, this question tests your ability to differentiate between basic aggregation functions—a common trap is confusing DISTINCTCOUNT with COUNTROWS, which counts all rows in a table rather than unique values in a column. To remember, think of DISTINCTCOUNT as the “unique counter” for a single column, while COUNTROWS is for entire tables. A quick memory tip: “Distinct means different, so DISTINCTCOUNT gives you the count of different items.”
This PL-300 practice question tests your understanding of model the data. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
You have a Power BI model with a table 'Sales' and a related 'Product' table. You want to count the number of distinct products sold. Which DAX expression should you use?
COUNTROWS(Sales)
Why wrong: COUNTROWS counts all rows.
COUNT(Sales[ProductID])
Why wrong: COUNT counts non-blank cells, not distinct.
DISTINCTCOUNT(Sales[ProductID])
DISTINCTCOUNT counts unique values.
COUNTA(Sales[ProductID])
Why wrong: COUNTA counts non-blank values.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
DISTINCTCOUNT(Sales[ProductID])
Option C is correct because DISTINCTCOUNT counts unique values. Option A is wrong because COUNT counts non-blank cells. Option B is wrong because COUNTA counts non-blank values. Option D is wrong because COUNTROWS counts rows.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
COUNTROWS(Sales)
Why it's wrong here
COUNTROWS counts all rows.
COUNT(Sales[ProductID])
Why it's wrong here
COUNT counts non-blank cells, not distinct.
DISTINCTCOUNT(Sales[ProductID])
Why this is correct
DISTINCTCOUNT counts unique values.
Related concept
Read the scenario before looking for a memorised answer.
COUNTA(Sales[ProductID])
Why it's wrong here
COUNTA counts non-blank values.
Common exam traps
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Identify which PL-300 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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FAQ
Model the data — This question tests Model the data — Read the scenario before looking for a memorised answer..
The correct answer is: DISTINCTCOUNT(Sales[ProductID]) — Option C is correct because DISTINCTCOUNT counts unique values. Option A is wrong because COUNT counts non-blank cells. Option B is wrong because COUNTA counts non-blank values. Option D is wrong because COUNTROWS counts rows.
Identify which PL-300 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 21, 2026
This PL-300 practice question is part of Courseiva's free Microsoft certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PL-300 exam.
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