PL-300 Prepare the data Practice Question
You are a Power BI data analyst for a financial services company. You have a Power Query query that combines data from multiple Excel workbooks stored in a SharePoint folder. The workbooks have a consistent structure. You need to ensure that when new workbooks are added to the folder, the query automatically includes them upon refresh. You also need to minimize the risk of query failures due to schema changes. What should you do?
⚠ Common exam trap
The trap here is assuming that the 'Combine Files' feature automatically handles all schema changes without additional configuration.
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
✓
Use the SharePoint Folder connector, filter to the relevant files, combine binaries, and then use a transformation that selects only the required columns and handles missing columns.
The most robust approach is to use the SharePoint Folder connector to automatically pick up new files, then combine the binaries. After combining, explicitly select only the columns needed and handle missing columns gracefully, for example by using Table.SelectColumns with MissingField.UseNull. This ensures that new files are included and that schema variations do not break the query. Simply combining without these safeguards leaves the query vulnerable to schema changes.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Use the SharePoint Folder connector, filter to the relevant files, combine binaries, and then use a transformation that selects only the required columns and handles missing columns.
Why this is correct
This approach automatically includes new files because it uses the folder connector and combines binaries. By explicitly selecting only the required columns and handling missing columns (e.g., using Table.SelectColumns with MissingField.UseNull), you minimize the risk of failures due to schema changes such as added or removed columns. This is a robust pattern for combining files with potential schema evolution.
- ✗
Use the SharePoint Folder connector, filter to the relevant files, combine binaries, and then remove the 'Changed Type' step.
Why it's wrong here
Removing the 'Changed Type' step can help avoid type conversion errors when schemas change, but it may also lead to incorrect data types downstream. It does not fully address schema changes like new or renamed columns. The combine operation may still fail if the structure differs significantly. This is a partial mitigation, not a complete solution.
- ✗
Use the SharePoint Folder connector, filter to the relevant files, and then use the 'Combine Files' button without any further transformations.
Why it's wrong here
The 'Combine Files' button creates a query that automatically includes new files, but it does not handle schema changes well. If a new file has a different structure, the combined query may fail or produce incorrect results. It does not minimize the risk of query failures due to schema changes. Additional transformations are needed to select columns and handle variations.
- ✗
Use the SharePoint Folder connector, filter to the relevant files, combine binaries, and then promote headers.
Why it's wrong here
This approach combines all files but does not inherently handle schema changes. If a new file has additional columns or different column names, the combine operation may fail or produce errors. While it automatically includes new files, it does not minimize the risk of query failures due to schema changes. Additional steps like removing changed types or using a robust transformation are needed.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Microsoft exam blueprint
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.