DA0-002 Data Acquisition and Preparation Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✓

  SELECT product_id, SUM(sales_amount) FROM sales GROUP BY product_id HAVING COUNT(*) > 50 ORDER BY SUM(sales_amount) DESC LIMIT 5

  Why this is correct

  HAVING filters grouped rows after aggregation, so COUNT(*) > 50 removes products with 50 or fewer sales before ranking. ORDER BY SUM(sales_amount) DESC with LIMIT 5 then returns the five highest-revenue products. WHERE cannot reference aggregates, making HAVING the only clause satisfying both the sales-count threshold and the top-5 constraint.

• ✗

  SELECT product_id, SUM(sales_amount) FROM sales WHERE COUNT(*) > 50 GROUP BY product_id ORDER BY SUM(sales_amount) DESC LIMIT 5

  Why it's wrong here

  WHERE COUNT(*) > 50 is invalid because aggregates cannot appear in WHERE, and filtering before grouping would exclude rows before totals are computed. HAVING applies the condition after GROUP BY. HAVING is correct when the requirement is filtering groups by an aggregate count.

• ✗

  SELECT product_id, SUM(sales_amount) FROM sales GROUP BY product_id HAVING COUNT(*) > 50 ORDER BY SUM(sales_amount) ASC LIMIT 5

  Why it's wrong here

  ORDER BY SUM(sales_amount) ASC returns the five lowest-selling products, the inverse of the top five requested. The HAVING COUNT(*) > 50 filter is correctly placed, so only the sort direction fails. DESC would be correct when the analyst wants the highest totals first.

• ✗

  SELECT product_id, SUM(sales_amount) FROM sales GROUP BY product_id WHERE COUNT(*) > 50 ORDER BY SUM(sales_amount) DESC LIMIT 5

  Why it's wrong here

  WHERE cannot contain aggregate functions; COUNT(*) is only valid in HAVING after GROUP BY. This query errors rather than returning results. HAVING is correct when filtering grouped rows by an aggregate such as COUNT(*) > 50, which is exactly the requirement here.