PL-300 Practice Test 4 — 25 Questions

Question 1

You are designing a data model for a sales analysis report. The source data includes a Sales table with columns: OrderID, CustomerID, ProductID, OrderDate, Quantity, and UnitPrice. You also have a Customers table and a Products table. Which approach best optimizes query performance and storage?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Create a star schema with Sales as a fact table and Customers and Products as dimension tables.. A star schema optimizes query performance and storage in Power BI by separating transactional data (Sales fact table) from descriptive attributes (Customers and Products dimension tables). This reduces data duplication, improves compression, and enables efficient aggregations and filter propagation via one-to-many relationships, which is the recommended modeling approach for analytical workloads.

Answer

Create separate fact tables for each dimension.

Answer

Create a single flat table by joining all columns from Sales, Customers, and Products into one table.

Answer

Create a snowflake schema by normalizing Customers into multiple related tables.

Question 2

You are preparing a Power BI dataset that includes a table 'Products' imported from an Excel workbook. The table has a column 'ProductCode' that contains values like 'A100', 'B200', etc. You need to create a new column that extracts the numeric part of the code (e.g., 100, 200) and uses it as an integer. Which Power Query transformation should you use?

Accepted Answer

Add a Custom Column with the formula Text.Select([ProductCode], {"0".."9"}) and change the type to Whole Number.. Using Text.Select with a list of digits extracts only the numeric characters from the code, regardless of the letter prefix. This creates a text column that can then be converted to an integer. Other methods are either too specific to certain prefixes or extract the wrong portion. Text.Select is the most flexible and correct approach.

Answer

Use the Replace Values transformation to replace 'A' and 'B' with an empty string, then change the type.

Answer

Use the Extract transformation and select 'Text Before Delimiter'.

Answer

Use the Split Column transformation by delimiter 'A' and keep the second part.

Question 3

You have a Power BI data model with a 'Date' table that contains continuous dates from January 1, 2020, to December 31, 2025. The 'Sales' table has a relationship with the 'Date' table. You need to create a measure that calculates the total sales for the last 12 months from the current context. Which DAX function should you use?

Accepted Answer

DATESINPERIOD. The DATESINPERIOD function is correct because it returns a contiguous set of dates from a specified start date (the last date in the current context) going back a given number of intervals (12 months). This allows the measure to dynamically calculate total sales for the trailing 12 months relative to any filter context, such as a specific year or month.

Answer

PREVIOUSMONTH

Answer

DATEADD

Answer

SAMEPERIODLASTYEAR

Question 4

You are a data analyst for a financial services company. You have a Power BI dataset that combines data from two sources: a CSV file in SharePoint Online and an on-premises SQL Server database. The CSV file contains exchange rates that are updated daily. The SQL Server database contains transaction data. You need to ensure that the dataset can be refreshed automatically in the Power BI service. The CSV file is updated at 6:00 AM daily, and the SQL Server database is updated continuously. You have already published the report. What should you do to enable automated refresh?

Accepted Answer

Install and configure an on-premises data gateway, then set up a scheduled refresh.. The on-premises SQL Server database requires an on-premises data gateway to bridge the Power BI service with the local network. Even though the CSV file is in SharePoint Online, the dataset combines both sources; the gateway is mandatory for the SQL Server component. Without it, scheduled refresh cannot access the on-premises data, and the dataset will fail to refresh automatically.

Answer

Use Power Automate to refresh the dataset after the CSV is updated.

Answer

Enable incremental refresh for the SQL Server table to reduce refresh time.

Answer

Configure a scheduled refresh in the dataset settings. The gateway is not required because the CSV file is in SharePoint Online.

Question 5

You are a Power BI data analyst for a manufacturing company. You have a report with a line chart showing daily production output over the past year. Users report that the line chart is cluttered and difficult to read due to daily fluctuations. You need to add analytics features to the line chart to help users identify trends and outliers. Which two features should you add? (Choose two.)

Accepted Answer

Trend line. Adding a trend line helps smooth out daily fluctuations and reveals the overall direction of production output. Anomaly detection automatically identifies and highlights unusual data points, making outliers immediately visible. Together, these features make the line chart easier to interpret. Forecast, constant line, and error bars do not directly address the need to identify trends and outliers in historical data.

Answer

Error bars

Answer

Forecast

Answer

Constant line

Question 6

You are preparing data in Power BI Desktop. You have a table with a column 'CustomerID' that contains duplicate values. You need to create a relationship to another table that also has 'CustomerID'. However, the relationship requires unique values in at least one of the tables. What should you do?

Accepted Answer

Remove duplicate rows from the 'CustomerID' column in the dimension table.. To create a relationship in Power BI, at least one table must have unique values in the column used for the relationship. By removing duplicate rows from the 'CustomerID' column in the dimension table (which should contain unique identifiers), you ensure that the dimension table has unique values, allowing a one-to-many relationship to be established with the fact table. This is a standard data modeling practice in Power BI to enforce referential integrity.

Answer

Create a composite key using multiple columns.

Answer

Use the 'Merge Queries' feature to combine the tables into one.

Answer

Change the data type of 'CustomerID' to text.

Question 7

You manage a Power BI deployment that uses deployment pipelines. After promoting content from Development to Test, you notice that the Test workspace dataset uses a different data source than expected. What is the most likely reason?

Accepted Answer

The dataset parameters were not configured in the deployment pipeline rules.. Deployment pipeline rules allow you to configure dataset parameters (such as data source paths) to differ between pipeline stages. If these rules are not set, the dataset retains the data source configuration from the source stage (Development), causing the Test workspace to use an unexpected data source. The pipeline deploys the dataset artifact, but without parameter overrides, the data source connection string remains unchanged.

Answer

The pipeline didn't deploy the dataset because it was already in Test.

Answer

The data source credentials were not applied during deployment.

Answer

The Test workspace has a separate dataset that was manually created.

Question 8

You are modeling a many-to-many relationship between 'Student' and 'Class' tables. Which approach should you use in Power BI to handle this?

Accepted Answer

Add a bridge table with composite keys. A many-to-many relationship in Power BI requires a bridge (or junction) table that contains composite keys (e.g., StudentID and ClassID) to resolve the relationship into two one-to-many relationships. This allows Power BI to properly filter and aggregate data across both tables without ambiguity.

Answer

Merge both tables into one

Answer

Use bidirectional cross-filtering

Answer

Create a single one-to-many relationship

Question 9

A Power BI report contains a page with many visuals that use a large DirectQuery dataset. The report is slow to load. Which design change would most improve the initial page load time?

Accepted Answer

Reduce the number of visuals on the page. Reducing the number of visuals on the page directly decreases the number of queries sent to the DirectQuery source during initial page load. Each visual in a DirectQuery model typically generates at least one separate query against the source database, so fewer visuals means fewer concurrent queries and less data transferred, which significantly improves load time.

Answer

Increase the default page-level filter to limit data

Answer

Use a slicer to let users choose what to see

Answer

Create aggregations on the dataset

Question 10

You have a Power BI report that uses a dataset with many columns. You want to reduce the dataset size by removing columns that are not used in any report visual. What is the best practice?

Accepted Answer

Remove the columns in Power Query Editor before loading. Removing columns in Power Query Editor before they are loaded into the data model physically excludes them from the dataset, reducing its size and improving performance. This is the only method that prevents unused columns from consuming memory and storage in the in-memory VertiPaq engine.

Answer

Use the Q&A feature to exclude columns

Answer

Apply report-level filters to exclude the columns

Answer

Hide the columns in the model view

Question 11

You are connecting to an Excel workbook stored in Microsoft SharePoint Online. You want to refresh the data in Power BI service without manual intervention. Which type of gateway is required?

Accepted Answer

No gateway is required. When connecting to an Excel workbook stored in Microsoft SharePoint Online, the data source resides entirely in the cloud. Power BI service can directly access SharePoint Online via its cloud-to-cloud connectivity using the same Microsoft Entra ID authentication context. Therefore, no on-premises data gateway is required for scheduled refresh because the data never traverses an on-premises network.

Answer

On-premises data gateway (standard mode)

Answer

On-premises data gateway (personal mode)

Answer

Virtual network (VNet) gateway

Question 12

You are importing data from an Excel workbook that has multiple worksheets. You only need data from the 'Sales' worksheet. When you connect via Power Query, all worksheets appear in the Navigator. What should you do to load only the 'Sales' worksheet?

Accepted Answer

Select the 'Sales' worksheet in Navigator and click 'Load'. In Power Query, the Navigator pane allows you to select specific worksheets or tables to load. Selecting the 'Sales' worksheet and clicking 'Load' imports only that data into your data model, avoiding unnecessary data. This is the most efficient method because it directly targets the required worksheet without extra steps.

Answer

Load all worksheets, then delete the unwanted ones

Answer

Select all worksheets and click 'Load'

Answer

Select the 'Sales' worksheet and click 'Transform Data'

Question 13

During data refresh in Power BI, an error occurs: 'The column 'OrderID' of the table 'Orders' contains a duplicate value and this column is part of a primary key.' The table 'Orders' is imported from an Azure SQL database. What is the most likely cause of this error?

Accepted Answer

The source table has duplicate 'OrderID' values.. The error message explicitly states that the 'OrderID' column contains a duplicate value and is part of a primary key. In Power BI, when importing from a source like Azure SQL Database, the data model enforces uniqueness on primary key columns. If the source table has duplicate 'OrderID' values, the refresh fails because Power BI cannot maintain the required unique constraint.

Answer

The 'Orders' table was reordered in Power Query.

Answer

Data type mismatch between the source and Power BI.

Answer

A calculated column is referencing the 'Orders' table.

Question 14

You are importing a large dataset from a CSV file using Power Query. The file contains 50 columns, but you only need 10 for your report. What is the most efficient way to reduce the amount of data loaded into the model?

Accepted Answer

Remove the unnecessary columns in Power Query before loading.. Power Query processes data before it enters the Power BI model. Removing unnecessary columns at the query stage reduces the amount of data loaded into memory, improving performance and reducing storage. This is the most efficient approach as it minimizes the dataset size from the start, unlike post-load methods that still consume resources.

Answer

Load all columns and then hide the unnecessary ones in the report.

Answer

Use a SQL query to select only the needed columns if the data source supports it.

Answer

Create a DAX calculated table that selects only the needed columns.

Question 15

A company uses Power BI to analyze sales data from a SQL Server database. The database contains a table 'Sales' with 10 million rows. The business analysts need to create daily reports that aggregate sales by region and product category. To optimize report performance, which data preparation technique should be applied?

Accepted Answer

Perform aggregation in SQL before importing.. Performing aggregation in SQL before importing reduces the data volume from 10 million rows to a much smaller aggregated result set. This minimizes memory consumption and speeds up report rendering in Power BI, as the heavy lifting is done on the SQL Server engine rather than in Power Query or the Power BI data model.

Answer

Increase the row limit in Power Query to load all rows.

Answer

Remove unused columns from the query.

Answer

Import the entire table and aggregate in Power BI.

Question 16

Which TWO are required components of a Power BI Paginated Report?

Accepted Answer

A dataset. In Power BI Paginated Reports, every report must be bound to at least one dataset (option C), which defines the fields and query results the report's tables, matrices, and other regions render. That dataset in turn must be backed by a data source (option D), the connection object that specifies the provider and connection string used to retrieve the data. Together, the data source and dataset form the minimum required data-retrieval components of a paginated report. A subscription (option A) is an optional delivery mechanism for scheduled report distribution, not a required report component. A map visual (option B) is just one optional report item type, and a query parameter (option E) is an optional filtering/parameterization feature, neither of which is mandatory for a paginated report to exist.

Answer

A subscription

Answer

A map visual

Answer

A query parameter

Question 17

You are a business analyst at a manufacturing company. You receive weekly CSV files from different plants. Each file contains columns: PlantID, Date, ProductID, UnitsProduced, and ScrapUnits. However, the files sometimes have missing values in the ScrapUnits column, and occasionally there are duplicate rows (same PlantID, Date, ProductID). You need to prepare a clean dataset for reporting. The requirements are:
1. Combine all CSV files from a folder into a single table.
2. Replace null values in ScrapUnits with 0.
3. Remove duplicate rows based on PlantID, Date, and ProductID, keeping the first occurrence.
4. Ensure the data types are appropriate (e.g., Date as date, UnitsProduced as whole number).

Which sequence of Power Query steps should you use?

Accepted Answer

Connect to folder, combine files, replace nulls, remove duplicates, set data types.. It follows the proper Power Query order: connect to the folder and combine the CSV files first, then replace null values in ScrapUnits with 0, then remove duplicate rows based on PlantID, Date, and ProductID keeping the first occurrence, and finally set the data types (Date as date, UnitsProduced as whole number). Replacing nulls before removing duplicates ensures that duplicate detection and the retained first row are based on complete data rather than nulls that could later change values. Setting data types last avoids type-conversion errors on text values that may still contain nulls or duplicates. Option A replaces nulls before combining, which is inefficient and may not apply consistently across all files; Option B sets data types before replacing nulls, which can cause conversion errors; Option C removes duplicates before replacing nulls, so null ScrapUnits values could affect which row is kept.

Answer

Connect to folder, replace nulls in each file, combine files, remove duplicates, set data types.

Answer

Connect to folder, combine files, set data types, replace nulls, remove duplicates.

Answer

Connect to folder, combine files, remove duplicates, replace nulls, set data types.

Question 18

Which TWO actions can improve data refresh performance in Power BI?

Accepted Answer

Disable load for intermediate queries used only for reference.. Option C is correct because disabling load on intermediate queries that are only used for reference prevents those staging tables from being materialized into the dataset, reducing the amount of data processed and stored during refresh. Option D is correct because filtering rows at the source (for example, using query folding or a WHERE clause in the source query) reduces the volume of data transferred and loaded, which directly speeds up refresh. Option A is not correct because merging all queries into one can create unnecessary complexity and may break query folding rather than improve performance. Option B is not correct because calculated columns in Power Query are computed during refresh and can actually slow it down compared to DAX calculated columns, which are computed at query time. Option E is not correct because keeping all source columns increases data volume and memory usage, which harms rather than improves refresh performance.

Answer

Merge all queries into a single query.

Answer

Add calculated columns in Power Query instead of DAX.

Answer

Keep all columns from the source data to avoid re-importing.

Question 19

You have a Power BI data model with a 'Sales' fact table and a 'Date' dimension. You need to create a calculated column in the 'Sales' table that shows the fiscal year based on a 'Date' column. The fiscal year starts on July 1. Which DAX expression should you use?

Accepted Answer

SWITCH(TRUE(), MONTH(Sales[Date]) >= 7, YEAR(Sales[Date]), YEAR(Sales[Date])-1). It uses SWITCH with TRUE() to evaluate a logical condition: if the month of the date is July or later (MONTH >= 7), it returns the current year; otherwise, it returns the previous year. This correctly implements a fiscal year starting on July 1, as required.

Answer

YEAR(Sales[Date])

Answer

YEAR(Sales[Date]) + 1

Answer

FORMAT(Sales[Date], "YYYY")

Question 20

You are loading data from a folder containing multiple Excel files with identical structure. Some files have inconsistent column names due to manual edits. You need to ensure that all data is loaded correctly without errors. What should you do in Power Query?

Accepted Answer

Use the 'Combine Files' feature with a sample file, then in the transformation step, promote headers and rename columns using a mapping table.. The 'Combine Files' feature in Power Query uses a sample file to infer the schema, and then you can apply transformations like promoting headers and renaming columns using a mapping table to handle inconsistent column names across files. This ensures all data loads without errors by standardizing the column names before combining.

Answer

Use 'Merge Queries' to join the files based on row position.

Answer

Change the data source to a SharePoint folder and use 'Load to Data Model' directly.

Answer

In Power Query, use 'Enter Data' to manually create the schema.