Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
A company uses Azure SQL Database for an e-commerce platform. The Orders table has columns: OrderID (primary key, clustered), CustomerID, OrderDate, TotalAmount. Queries frequently filter on CustomerID and a range of OrderDate, and then sort the results by OrderDate in descending order. The queries also return the TotalAmount column. Which indexing strategy will most improve query performance for these operations?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Best answer
Create a nonclustered index on (CustomerID, OrderDate DESC) with included column TotalAmount
This index directly supports the filter on CustomerID and the range/order on OrderDate, and includes TotalAmount to avoid key lookups, making it the most efficient.
B
Distractor review
Create a nonclustered index on (OrderDate DESC, CustomerID) with included column TotalAmount
This index orders by date first, so for a specific CustomerID, the database would need to scan a potentially large range of dates before applying the CustomerID filter, which is less efficient.
C
Distractor review
Change the clustered index to be on (CustomerID, OrderDate DESC)
Changing the clustered index from the primary key OrderID could disrupt other queries and operations; also, a clustered index on these columns might cause page splits and fragmentation due to sequential inserts by OrderID.
D
Distractor review
Create a nonclustered index on (OrderDate DESC) without including TotalAmount
This index does not filter by CustomerID, so the query would need to scan many rows or perform a key lookup for each row, resulting in poor performance.
Common exam trap
Common exam trap: answer the scenario, not the keyword
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.
Technical deep dive
How to think about this question
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.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
- Use explanations to understand the rule behind the answer.
TExam Day Tips
- Underline the problem statement mentally.
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Related practice questions
Related DP-900 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
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Question 2
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Question 3
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Question 4
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Question 5
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Question 6
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FAQ
Questions learners often ask
What does this DP-900 question test?
Read the scenario before looking for a memorised answer.
What is the correct answer to this question?
The correct answer is: Create a nonclustered index on (CustomerID, OrderDate DESC) with included column TotalAmount — The optimal index must support both the filter predicates (CustomerID and OrderDate range) and the sort order (OrderDate descending). A nonclustered index on (CustomerID, OrderDate DESC) with included column TotalAmount allows the query to seek directly on CustomerID, then scan only the relevant OrderDate range in descending order without a separate sort operation, and retrieve TotalAmount from the included column without key lookups. Option B (OrderDate DESC, CustomerID) is less efficient because it requires scanning a larger range of OrderDate first before filtering by CustomerID. Option C would change the clustered index, which is not advisable as OrderID is already clustered and changing it could impact other queries. Option D lacks CustomerID filtering, leading to a inefficient scan.
What should I do if I get this DP-900 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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