PL-300 Prepare the data Practice Question
You are importing data from an Excel workbook that contains multiple sheets. You only need data from the 'Sales' sheet. In Power Query Editor, what should you do to load only that sheet?
⚠ Common exam trap
Watch out — candidates often think they can use a filter or query folding to exclude entire sheets after loading, but Power Query treats each sheet as a separate table, not as rows within a single table, so filtering cannot remove sheets.
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
✓
In the Navigator dialog, select the 'Sales' sheet and click 'Transform Data'.
In Power Query Editor, the Navigator dialog allows you to preview and select specific tables or sheets from a data source before loading. By selecting the 'Sales' sheet and clicking 'Transform Data', you load only that sheet into Power Query Editor for transformation, avoiding unnecessary data. This is the correct and efficient method to import a single sheet from a multi-sheet Excel workbook.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Load all sheets, then delete the queries for sheets you don't need.
Why it's wrong here
Selecting every sheet from the Excel workbook creates a Power Query object for each, causing Power BI to read and stage data you will never use. You then must manually delete those queries, but the initial import still incurs needless memory, storage, and refresh time in the data model. The proper approach is to limit the source at the very first step—choose only the Sales sheet in Navigator—so no wasted queries are ever created.
- ✓
In the Navigator dialog, select the 'Sales' sheet and click 'Transform Data'.
Why this is correct
In the Navigator dialog, each worksheet and named table appears as a previewable source; choosing the 'Sales' sheet and clicking 'Transform Data' sends only that sheet's data into Power Query Editor as the single source for a new query. This lets you filter rows, change data types, or add custom columns before loading, while leaving every other sheet unread and out of the data model. This is the efficient, supported workflow for importing a specific worksheet.
- ✗
Use a filter transform to exclude rows from other sheets.
Why it's wrong here
A filter transform in Power Query operates on the rows of a single query that is already bound to one sheet or table. Since each Excel worksheet is a separate data source, filtering rows cannot deselect or exclude entire sheets; it only removes records from the table you have already imported. Attempting to gather all sheets and then filter on a sheet name merely partitions rows, it does not prevent the other sheets from being loaded into memory and refreshed.
- ✗
Select the entire workbook and then filter out other sheets in Power Query.
Why it's wrong here
Choosing the entire workbook in Navigator produces a query that represents the workbook's contents as a structural set of items, but Power Query provides no direct 'filter sheets' transform—you cannot just drop other worksheets from the Used Items list after the fact. To isolate Sales from that structure, you would have to expand the workbook tables and apply custom logic on sheet metadata, which is brittle and unnecessary. The supported workflow is to pick the specific sheet in Navigator before creating the query.
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