PL-300 Prepare the data Practice Question
Exhibit
Refer to the exhibit.
EVALUATE
SUMMARIZE(
'Sales',
'Product'[Category],
"Total Sales", SUM('Sales'[Amount])
)You are reviewing a DAX query in DAX Studio. The exhibit shows a query that returns a table. What is the purpose of the SUMMARIZE function in this query?
⚠ Common exam trap
Test-takers frequently confuse SUMMARIZE with functions that add calculated columns (ADDCOLUMNS) or filter tables (FILTER), leading them to pick options B or D, when in fact SUMMARIZE is specifically for grouping and aggregation.
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
✓
To group sales by product category and compute total sales
The SUMMARIZE function in DAX is used to group rows from a table based on one or more columns (here, Product Category) and then compute an aggregated value (Total Sales) using a SUM expression. The query returns a new table with one row per category and the corresponding total sales, which is the standard purpose of SUMMARIZE for grouping and aggregation.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
To group sales by product category and compute total sales
Why this is correct
SUMMARIZE evaluates a table expression over the Sales table, grouping rows by the Product[Category] column and computing the sum of Sales[Amount] for each distinct category. The result is a new two-column table (Category and Total Sales), with one row per category. This is the correct interpretation because SUMMARIZE is explicitly designed for grouped aggregation, not for altering the original table or its schema.
- ✗
To add a calculated column to the Sales table
Why it's wrong here
A calculated column is added to an existing table in the data model via the Data View or computed with CALCULATE/ADDCOLUMNS inside a table expression, but SUMMARIZE returns a brand-new standalone table in a DAX query. It does not modify the Sales table by adding a column; rather, it projects grouped columns and aggregates. The presence of SUM(Sales[Amount]) in the query might suggest a column, but it is an aggregation over a group, not a persistent column definition.
- ✗
To add a new row for total sales per category
Why it's wrong here
SUMMARIZE creates a new table object rather than inserting rows into the Sales table. The rows it generates represent each unique product category, not additional rows appended to an existing table with a 'Total' category for overall sales. While SUMMARIZE can include a grand total row if the query is written with ROLLUP, the basic pattern shown in the exhibit simply groups by Category and computes per-category totals, not an added summary row to the Sales table.
- ✗
To filter the Sales table by Product Category
Why it's wrong here
Filtering the Sales table by Product Category would narrow the rows being considered (e.g., via CALCULATE with a filter argument or a FILTER function) and preserve the original granularity. SUMMARIZE instead collapses the Sales table by grouping rows into categories and computing an aggregate (SUM of Amount) per group. It does not reduce the number of rows in the Sales table; it produces an entirely new summary table, so calling it a filtering operation misrepresents its purpose and output.
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