- A
Create a calculated table in DAX using SUMMARIZE(Diagnosis, Diagnosis[DiagnosisCode], "Description", FIRSTNONBLANK(Diagnosis[DiagnosisDescription], 1)) and use that table for the relationship.
This creates a distinct DiagnosisCode table with one description, allowing a one-to-many relationship.
- B
In Power Query, remove duplicate rows based on DiagnosisCode, keeping the first occurrence.
Why wrong: This removes data permanently, which may not be desired.
- C
Create a many-to-many relationship between PatientVisits and Diagnosis.
Why wrong: Many-to-many relationships are complex and may not be supported directly.
- D
Create a composite key in PatientVisits by concatenating VisitID and DiagnosisCode, and relate to Diagnosis on that key.
Why wrong: That would not resolve duplicates in Diagnosis.
Quick Answer
The correct approach is to create a calculated table in DAX using SUMMARIZE(Diagnosis, Diagnosis[DiagnosisCode], "Description", FIRSTNONBLANK(Diagnosis[DiagnosisDescription], 1)) and then build the relationship from PatientVisits to this new table. This works because SUMMARIZE groups by the duplicate dimension key, collapsing multiple rows into one unique row per DiagnosisCode, while FIRSTNONBLANK picks the first non-empty description, preserving data integrity without deleting any original rows. On the PL-300 exam, this scenario tests your ability to handle data quality issues in a star schema without losing information—a common trap is reaching for Power Query to remove duplicates, which permanently discards rows and violates the requirement to keep all data. The key insight is that calculated tables are virtual and non-destructive, making them ideal for resolving duplicate dimension keys while maintaining referential integrity. Memory tip: think “SUMMARIZE to summarize duplicates, FIRSTNONBLANK to keep the first good description.”
PL-300 Model the data Practice Question
This PL-300 practice question tests your understanding of model the data. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 are a Power BI developer for a healthcare organization. You have a semantic model that contains a table named PatientVisits with columns: VisitID, PatientID, VisitDate, DiagnosisCode, and Charges. You have a separate table named Diagnosis with columns: DiagnosisCode, DiagnosisDescription, and Category. The Diagnosis table contains duplicate rows for the same DiagnosisCode but with different descriptions due to data entry errors. You need to create a relationship between PatientVisits and Diagnosis on DiagnosisCode. However, the duplicate values in Diagnosis prevent creating a one-to-many relationship. You must ensure that the relationship can be created without removing any rows from the Diagnosis table. What should you do?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Create a calculated table in DAX using SUMMARIZE(Diagnosis, Diagnosis[DiagnosisCode], "Description", FIRSTNONBLANK(Diagnosis[DiagnosisDescription], 1)) and use that table for the relationship.
Option A is correct: creating a calculated table that groups by DiagnosisCode and takes the first description resolves duplicates. Option B is wrong because removing duplicates in Power Query would remove rows permanently. Option C is wrong because you cannot create a relationship on a dash. Option D would create a many-to-many relationship, which is not ideal.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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 calculated table in DAX using SUMMARIZE(Diagnosis, Diagnosis[DiagnosisCode], "Description", FIRSTNONBLANK(Diagnosis[DiagnosisDescription], 1)) and use that table for the relationship.
Why this is correct
This creates a distinct DiagnosisCode table with one description, allowing a one-to-many relationship.
Related concept
Static NAT maps one inside address to one outside address.
- ✗
In Power Query, remove duplicate rows based on DiagnosisCode, keeping the first occurrence.
Why it's wrong here
This removes data permanently, which may not be desired.
- ✗
Create a many-to-many relationship between PatientVisits and Diagnosis.
Why it's wrong here
Many-to-many relationships are complex and may not be supported directly.
- ✗
Create a composite key in PatientVisits by concatenating VisitID and DiagnosisCode, and relate to Diagnosis on that key.
Why it's wrong here
That would not resolve duplicates in Diagnosis.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
- Static NAT maps one inside address to one outside address.
- PAT allows many inside hosts to share one public address using ports.
- Inside local and inside global describe the private and translated addresses.
- NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
- Identify inside and outside interfaces first.
- Check whether the scenario needs static NAT, dynamic NAT or PAT.
- Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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. NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated. 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.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related PL-300 NAT questions on configuration and troubleshooting.
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FAQ
Questions learners often ask
What does this PL-300 question test?
Model the data — This question tests Model the data — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Create a calculated table in DAX using SUMMARIZE(Diagnosis, Diagnosis[DiagnosisCode], "Description", FIRSTNONBLANK(Diagnosis[DiagnosisDescription], 1)) and use that table for the relationship. — Option A is correct: creating a calculated table that groups by DiagnosisCode and takes the first description resolves duplicates. Option B is wrong because removing duplicates in Power Query would remove rows permanently. Option C is wrong because you cannot create a relationship on a dash. Option D would create a many-to-many relationship, which is not ideal.
What should I do if I get this PL-300 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related PL-300 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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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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