PL-300 Visualize and analyze the data Practice Question
Which TWO actions can you perform using Power BI Desktop's Query Editor? (Choose two.)
⚠ Common exam trap
A common trap is thinking that Query Editor can create relationships, but relationship creation is a data modeling task performed in Model view. Some may confuse merging tables with creating relationships, but merging simply combines data into a new table.
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
✓
Merge two tables based on a common column.
In Power BI Desktop's Query Editor, you can merge two tables based on a common column using the 'Merge Queries' feature (option B) and remove duplicate rows using the 'Remove Duplicates' feature (option D). Creating a relationship between tables (option C) is not performed in Query Editor; it is done in the Model view after loading data. Defining row-level security roles (option A) and creating DAX measures (option E) are also not available in Query Editor — roles are managed in the Modeling tab or Power BI Service, and measures are created in the Report or Data view.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Define row-level security (RLS) roles.
Why it's wrong here
Row-level security (RLS) defines which rows different users can see, typically by creating roles in the Model view using 'Manage Roles' and writing DAX filter expressions for tables. Query Editor is a data-shaping environment and has no concept of users or security contexts; it cannot be used to set permissions or roles. Configuring RLS generally requires the data model to be completed first.
- ✓
Merge two tables based on a common column.
Why this is correct
The 'Merge Queries' feature in Query Editor combines rows from two tables based on a common column, supporting join kinds such as left outer, right outer, full outer, and inner. You can expand the resulting columns to bring in related fields, which is a common way to enrich one table with data from another. This operation is performed in Power Query before the data is loaded into the model.
- ✗
Create a relationship between two tables.
Why it's wrong here
While you can merge queries in Query Editor to combine data from two tables on a common column, this does not create a true relationship in Power BI's data model. A relationship is a metadata link between distinct tables, defined in the Model view by connecting foreign keys, not by physically reshaping data. Merging effectively denormalizes tables into a single table, which is a different operation from establishing a relationship.
- ✓
Remove duplicate rows from a table.
Why this is correct
Query Editor includes a 'Remove Duplicates' feature on the Home tab that examines one or more selected columns and removes rows where values in those columns repeat, keeping only the first occurrence. This is a data-cleaning transformation that is frequently used to ensure unique rows before loading data into the model. It is performed entirely in Power Query (M language), not in DAX or the model layer.
- ✗
Create a new measure using DAX.
Why it's wrong here
Measures are DAX formulas that are stored in the data model and evaluated dynamically based on report filters and slicers. The Creation of measures is done in the Report view or Model view using the formula bar, or in calculation groups—not in Power Query. Query Editor uses the Power Query M macro language for data transformation, and it has no mechanism to define DAX measures.
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