20+ practice questions focused on Prepare the data — one of the most tested topics on the Microsoft Power BI Data Analyst PL-300 exam. Each question includes a detailed explanation so you learn why the right answer is correct.
Start Prepare the data PracticeA 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?
Explanation: Option D is correct because 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.
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?
Explanation: Option D is correct because 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.
A data analyst needs to combine two queries in Power Query: 'Sales2023' and 'Sales2024', both with identical column structures. Which operation should the analyst use to append the rows from 'Sales2024' to 'Sales2023'?
Explanation: The Append Queries operation in Power Query is designed to combine rows from two or more tables with identical column structures, stacking the rows of 'Sales2024' beneath those of 'Sales2023'. This is the correct method because it preserves all columns and adds data vertically, which matches the requirement to append rows.
A Power BI report contains a table with a column 'Date' of type date. The report users need to filter data by fiscal year, which starts on April 1. What is the best practice to support this requirement during data preparation?
Explanation: Option A is correct because creating a separate date table in Power Query with a fiscal year column is the best practice for handling fiscal year filtering. This approach ensures the date dimension is independent of fact tables, supports star schema design, and allows you to define fiscal year logic (starting April 1) directly in M code during data preparation, which is more efficient and maintainable than using DAX calculated columns or tables.
When importing data from a CSV file, Power Query detects that the first row contains column headers. However, the actual data starts from row 2. The analyst notices that some rows have extra columns due to commas within quoted fields. What is the most efficient way to handle this issue?
Explanation: Option C is correct because the 'Split Column by Delimiter' feature in Power Query, when configured to split at each occurrence of the comma delimiter, correctly handles commas that appear inside quoted fields. Power Query's M engine respects the standard CSV quoting rules (RFC 4180), so quoted commas are not treated as delimiters. This approach is the most efficient as it requires no manual cleanup and preserves data integrity.
+15 more Prepare the data questions available
Practice all Prepare the data questions1. Baseline your knowledge
Start with 10 questions to gauge your current understanding of Prepare the data. This tells you whether you need a concept refresher or just practice.
2. Review every explanation
For each question — right or wrong — read the full explanation. Understanding why an answer is correct is more valuable than knowing the answer itself.
3. Focus on exam traps
Prepare the data questions on the PL-300 frequently use trap wording. Look for subtle differences in answers that test your precision, not just general knowledge.
4. Reach 80% consistently
Do repeated sessions until you score 80%+ three times in a row. Then move to mixed-mode practice to test cross-topic recall under realistic conditions.
The exact number varies per candidate. Prepare the data is tested as part of the Microsoft Power BI Data Analyst PL-300 blueprint. Practicing with targeted Prepare the data questions ensures you can handle any format or difficulty that appears.
Yes. Courseiva provides free PL-300 practice questions across all exam topics and domains. The platform includes topic-based practice, mock exams, missed-question review, bookmarked questions, and readiness tracking — no account required.
Difficulty is subjective, but Prepare the data is a high-priority exam concept tested in multiple ways — direct recall, scenario analysis, and command-output interpretation. Consistent practice is the best way to build confidence.
Launch a full Prepare the data practice session with instant scoring and detailed explanations.
Start Prepare the data Practice →