PL-300 Practice Test 12 — 15 Questions

Question 1

You are examining a Power BI dataflow configuration. The dataflow is scheduled to refresh the 'Sales' entity daily and the 'Product' entity hourly. However, the 'Product' entity refresh fails every hour with an error indicating the SharePoint list data source is not accessible. You need to diagnose the issue. What is the most likely cause?

Accepted Answer

The refresh interval is too frequent for the incremental granularity of 'Day'. Option A is correct because the 'Product' entity is configured to refresh hourly, but the dataflow's incremental refresh policy is set to a 'Day' granularity. Incremental refresh in Power BI requires the refresh frequency to align with or be less frequent than the incremental period; an hourly refresh on a daily partition causes the engine to attempt to query the entire day's data each time, which can lead to timeouts or errors if the source (SharePoint list) cannot handle the repeated full scans. The error 'data source is not accessible' often masks this underlying mismatch between refresh frequency and incremental granularity.

Answer

Incremental refresh is not supported for SharePoint list data sources

Answer

The workspace ID is missing from the dataflow configuration

Answer

The on-premises data gateway is not configured for the SharePoint list

Question 2

You have a Power BI data model that contains a fact table and a date dimension. The fact table has a column 'OrderDate' and the date dimension has a column 'Date'. You need to create a measure that calculates the total sales for the last complete month. The date dimension is marked as a date table. What DAX expression should you use?

Accepted Answer

CALCULATE(SUM(Sales[Amount]), PREVIOUSMONTH('Date'[Date])). Option D is correct because PREVIOUSMONTH returns a set of dates for the previous month relative to the last date in the current filter context. Since the date dimension is marked as a date table, time intelligence functions like PREVIOUSMONTH work correctly. CALCULATE then evaluates SUM(Sales[Amount]) over that month-long period, giving total sales for the last complete month.

Answer

CALCULATE(SUM(Sales[Amount]), DATESMTD('Date'[Date]))

Answer

CALCULATE(SUM(Sales[Amount]), 'Date'[Date] = DATE(2023,1,1))

Answer

TOTALMTD(SUM(Sales[Amount]), 'Date'[Date])

Question 3

You are cleaning a column that contains numbers stored as text, with occasional leading/trailing spaces and currency symbols. You apply the function above to the column. However, some rows return null even though the original text appears to be a valid number, such as '$ 1,234.56'. What is the most likely cause?

Accepted Answer

The function does not remove commas and currency symbols before conversion.. Option D is correct because the function shown (likely a custom M function or Power Query transformation) does not strip commas and currency symbols before attempting conversion. When the input '$ 1,234.56' is passed directly to a number conversion like Number.From or Number.FromText, the presence of the dollar sign, spaces, and comma causes the conversion to fail, returning null. The try...otherwise block only catches errors but does not clean the text, so the conversion still fails silently.

Answer

The try...otherwise block is not catching parsing errors.

Answer

Text.Clean removes necessary decimal separators.

Answer

The function is applied to the wrong data type column.

Question 4

You are combining CSV files from a folder. The code above returns an error because some CSV files have inconsistent column names and data types. You need to modify the solution to handle variations in column structure. What should you do?

Accepted Answer

Use the Folder connector's 'Combine Files' transform, which handles schema merging automatically.. Option D is correct because the 'Combine Files' transform in Power Query (Folder connector) automatically detects and merges columns from multiple CSV files, even when column names or data types vary. It uses a sample file to infer the schema and then applies transformations to handle inconsistencies, such as promoting headers and aligning data types, which resolves the error without manual intervention.

Answer

Change the delimiter to a semicolon and reconfigure the CSV parser.

Answer

Use Table.RemoveRows to remove rows that cause errors.

Answer

Add a custom column to each file to standardize data types before combining.

Question 5

You have a Sales table with columns: ProductID, Amount, Date. You create the calculated column above. However, the rank values are not as expected; all rows show 1. What is the most likely cause?

Accepted Answer

The expression SUM(Sales[Amount]) in a calculated column aggregates only the current row, resulting in the same value for all rows.. Option C is correct because in a calculated column, the SUM(Sales[Amount]) expression is evaluated in row context, meaning it aggregates only the current row's Amount value rather than the entire Sales table. Since every row has the same single-row aggregate, RANKX sees identical values for all rows and assigns rank 1 to each. To get correct ranking, you must use a measure or explicitly use ALL(Sales) in the expression to remove row context.

Answer

The Dense parameter forces all ranks to 1.

Answer

The DESC parameter is misspelled; it should be 'Desc'.

Answer

The RANKX function requires a measure, not a calculated column.

Question 6

You are connecting to an on-premises Oracle database from Power BI Service. The gateway is installed and configured. However, the scheduled refresh fails with an error indicating that the data source credentials are invalid. Which TWO steps should you take to resolve the issue? (Choose two.)

Accepted Answer

Update the data source credentials in the gateway settings in Power BI Service.. Option B is correct because the scheduled refresh failure indicates that the stored credentials for the on-premises Oracle data source in Power BI Service are invalid. You must update the data source credentials in the gateway settings under 'Manage gateways' in Power BI Service to provide a valid username and password that the gateway can use to authenticate against the Oracle database. Option C is correct because the gateway machine requires the Oracle client software (e.g., Oracle Data Access Components or ODP.NET) to be installed and configured, and the gateway must have network connectivity to the Oracle server; verifying these ensures the gateway can reach and authenticate with the database.

Answer

Re-publish the Power BI report from Power BI Desktop.

Answer

Edit the data source settings in Power BI Desktop and republish.

Answer

Reinstall the on-premises data gateway.

Question 7

You are creating a Power BI report for a marketing team. The data is stored in a folder of CSV files on a network drive that is accessible from your computer. You need to combine all CSV files into a single table in Power BI. The files have the same structure. What should you do in Power Query?

Accepted Answer

Use the 'Combine Files' transform after connecting to the folder.. Option B is correct because Power Query's 'Combine Files' transform is specifically designed to handle multiple CSV files with identical schemas stored in a folder. When you connect to the folder as a data source, Power Query automatically generates a sample file query and a transformation function that applies the same steps to all files, then combines the results into a single table. This is the most efficient and recommended approach for this scenario, avoiding manual appending or merging.

Answer

Connect to each CSV file individually and use Append Queries.

Answer

Use Merge Queries to join the files based on a common column.

Answer

Change the data source settings to treat the folder as a single data source.

Question 8

You are connecting to a large CSV file (10 GB) stored in Azure Blob Storage. You need to load the data into Power BI with optimal performance. Which THREE practices should you follow? (Choose three.)

Accepted Answer

Use Parquet format instead of CSV if possible.. Options A, C, and E are correct because splitting the file, filtering rows early, and using an efficient file format improve performance. Option B is incorrect because the Power BI service can handle large files, but the gateway is not needed for cloud storage. Option D is incorrect because importing all columns reduces performance; you should select only needed columns.

Answer

Import all columns and use Power BI to hide unused ones.

Answer

Use the on-premises data gateway to connect to Azure Blob Storage.

Question 9

You are profiling data in Power Query Editor. Which THREE tasks can you perform using the Column Profile feature?

Accepted Answer

Identify data type issues. The Column Profile feature in Power Query Editor provides a statistical summary of the data in a selected column, including value distribution, distinct counts, and data type detection. Option B is correct because the profile automatically highlights data type inconsistencies (e.g., numbers stored as text) by showing the 'Data Type' indicator and flagging errors, enabling you to identify and fix type issues before loading data.

Answer

Add a conditional column

Answer

Replace values

Question 10

You are using Power Query to transform a column 'FullName' containing values like 'Smith, John'. You need to split this into 'LastName' and 'FirstName' columns. Which THREE steps are required?

Accepted Answer

Use 'Split Column' by delimiter. Options A, B, and D are correct. Split Column by delimiter (A) with comma, then you might need to trim spaces (B) and rename columns (D). Option C is wrong because unpivot is not needed. Option E is wrong because merging is the opposite of splitting.

Answer

Unpivot columns

Answer

Merge the split columns back

Question 11

You are importing data from a folder containing multiple Excel files with the same structure. You use Power Query's 'Combine Files' feature. Which TWO statements about this process are correct?

Accepted Answer

It uses the first file as a template for transformation.. Option C is correct because when you use Power Query's 'Combine Files' feature, it uses the first file as a template to infer the schema and transformations. This sample file query defines how each subsequent file is processed, ensuring consistent column types and transformations across all files.

Answer

It automatically removes duplicate rows across files.

Answer

You can change the transformation order after combining.

Answer

It automatically creates relationships between files.

Question 12

You are preparing data for a star schema. Which THREE types of tables are typically included in a star schema?

Accepted Answer

Dimension tables. In a star schema, dimension tables (C) provide descriptive attributes for the measures stored in fact tables. They are denormalized to optimize query performance in tools like Power BI, enabling fast slicing and dicing of data without complex joins.

Answer

Staging tables

Answer

Bridge tables

Question 13

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.. Option C is correct because the logical order is: connect to folder, combine files, then clean data (replace nulls, remove duplicates) and set data types. Option A is incorrect because setting data types before cleaning can cause errors. Option B is incorrect because removing duplicates before replacing nulls may remove rows that could be fixed. Option D is incorrect because removing duplicates before combining files would apply to each file individually, not across files.

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 14

You are creating a star schema in Power BI. You have a fact table named Sales with columns: Date, ProductID, CustomerID, Quantity, and UnitPrice. You need to create a relationship between Sales and a Date dimension. Which column in the Date dimension should be used as the key to relate to the Date column in Sales?

Accepted Answer

DateKey. The correct answer is A: DateKey. In a star schema, the dimension table should have a unique key that matches the fact table's foreign key. The DateKey column is typically an integer or date without time, ensuring a one-to-many relationship. Option B (FullDate) might include time, causing granularity mismatch. Option C (Date) could work if unique, but DateKey is standard. Option D (DateID) is also plausible but less common; DateKey is the best practice.

Answer

DateID

Answer

Date

Answer

FullDate

Question 15

You have a Power BI model with a table named Orders that contains columns OrderDate, ShipDate, and CustomerID. You need to create a calculated column that computes the number of days between OrderDate and ShipDate. Which DAX expression should you use?

Accepted Answer

DATEDIFF(Orders[OrderDate], Orders[ShipDate], DAY). Option A is correct because the DATEDIFF function in DAX calculates the interval between two dates in the specified unit (DAY). This directly computes the number of days between OrderDate and ShipDate, which is the required result for the calculated column.

Answer

DATEADD(Orders[OrderDate], 1, DAY)

Answer

DAY(Orders[ShipDate] - Orders[OrderDate])

Answer

NETWORKDAYS(Orders[OrderDate], Orders[ShipDate])

PL-300 Practice Test 12 — 15 Questions

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PL-300 Practice Test 12 — 15 Questions

Exhibit