The answer is to create a one-to-many relationship from Customers to Orders with single direction. This is correct because in a star schema, the dimension table (Customers) should filter the fact table (Orders) through a one-to-many relationship, ensuring that selecting a customer shows only their orders while preventing reverse cross-filtering that could distort aggregations. On the PL-300 exam, this tests your understanding of model cardinality and filter flow, often appearing in scenario-based questions where a trap is to set the relationship as many-to-one or bidirectional, which would break the star schema’s intended unidirectional filtering. A key memory tip is “dimension filters down to facts, not up,” meaning the one side (dimension) always filters the many side (fact) in a single direction.
PL-300 Model the data Practice Question
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.
A data model has a table 'Orders' with columns: OrderID, CustomerID, OrderDate, Amount. There is a 'Customers' table with columns: CustomerID, CustomerName. To analyze orders by customer, what is the best practice for modeling the relationship?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create a one-to-many relationship from Customers to Orders with single direction.
Option A is correct because in a star schema, the Customers table (dimension) should have a one-to-many relationship to the Orders table (fact) filtered from the dimension side. This single-direction filter propagation ensures that when a customer is selected, only their orders are shown, while preventing unwanted cross-filtering from orders back to customers. This is the standard best practice for modeling dimension-to-fact relationships in Power BI.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Create a one-to-many relationship from Customers to Orders with single direction.
Why this is correct
This is the standard star schema approach, allowing filters from Customers to propagate to Orders.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Create a one-to-one relationship between Customers and Orders based on CustomerID.
Why it's wrong here
One-to-one is incorrect because one customer can have many orders.
✗
Create an inactive relationship and use USERELATIONSHIP in measures.
Why it's wrong here
This adds complexity; active relationship is preferred for default filtering.
✗
Create a many-to-one relationship from Orders to Customers with both directions.
Why it's wrong here
Many-to-one is correct but both directions unnecessary and may cause ambiguity.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse the direction of the relationship (thinking the fact table should be on the 'one' side) or overcomplicate the model by using inactive relationships or bidirectional filtering when a simple single-direction one-to-many is the correct and efficient choice.
Detailed technical explanation
How to think about this question
Under the hood, Power BI uses a single-direction filter context by default, meaning filters applied to the 'one' side (Customers) automatically propagate to the 'many' side (Orders) via the relationship. This is implemented through the VertiPaq engine, which stores relationship metadata in the form of a bitmap index for efficient filtering. In a real-world scenario, if you accidentally set bidirectional filtering, you might encounter circular dependencies or unexpected filter propagation when multiple dimension tables are involved, leading to incorrect aggregations.
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.
TExam Day Tips
→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.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
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
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Model the data — This question tests Model the data — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Create a one-to-many relationship from Customers to Orders with single direction. — Option A is correct because in a star schema, the Customers table (dimension) should have a one-to-many relationship to the Orders table (fact) filtered from the dimension side. This single-direction filter propagation ensures that when a customer is selected, only their orders are shown, while preventing unwanted cross-filtering from orders back to customers. This is the standard best practice for modeling dimension-to-fact relationships in Power BI.
What should I do if I get this PL-300 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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