Top Power BI Interview Questions Asked By Leading Companies:-
Hello Everyone , Checkout Top Power BI questions asked by leading companies.
- What is append, and what is the necessary condition to append queries?
Answer – Append in Power BI allows you to combine rows from multiple tables into one unified table. To append queries successfully, the tables should have identical column structures, meaning they must have the same number of columns and compatible data types. This ensures a smooth and accurate merge without data mismatches.
- What is incremental refresh, and would you implement it in your model?
Answer – Incremental refresh updates only new or modified data rather than reloading the entire dataset, optimizing performance and reducing refresh time, especially for large datasets. In a real-world setting, implementing incremental refresh is ideal for models with high-frequency data updates, as it streamlines performance and enhances efficiency.
- What error do we get when we have many-to-many relationships between two tables?
Answer – A circular dependency or ambiguity error can arise with many-to-many relationships because Power BI cannot clearly determine calculation paths. In such cases, itβs generally necessary to restructure with a bridge table or filter settings to resolve the ambiguity and ensure data accuracy across relationships.
- What are Relationship Modifiers?
Answer – Relationship Modifiers such as Cross-filter direction and Make this relationship active allow you to define how tables filter each other in a model. These settings are crucial for controlling data interaction flow, particularly in complex data models, as they govern how filtering and calculations propagate across tables.
- What is a Factless Fact Table?
Answer – A Factless Fact Table is a fact table that contains only foreign keys without numerical data (measurable facts). Itβs used to record occurrences of specific events or conditions, such as tracking student attendance or product promotions, and is helpful for capturing relationships between dimensions without requiring quantitative data.
- Can you give an example of Slowly Changing Dimensions?
Answer – Slowly Changing Dimensions (SCDs) refer to attributes in a dimension that change infrequently over time, such as a customerβs address or an employeeβs job role. A common approach is to maintain a history of changes, enabling tracking of attribute changes over time for accurate reporting.
- Tell me something about the Decomposition Tree visual, and how it is useful.
Answer – The Decomposition Tree In Power BI allows users to drill down into data hierarchies visually, breaking down data into subcategories. Itβs highly valuable for root cause analysis, as it enables users to explore data drivers at detailed levels, revealing insights and trends within complex data structures.
- What are the limitations of using Direct Query connection mode reports?
Answer – Direct Query mode allows real-time data access but has limitations. Complex calculations can result in slower performance, as each query is processed by the source. It also restricts certain transformations and DAX functions, making it less suitable for large data transformations within Power BI.
- Can you give a use case for using Bookmarks?
Answer – Bookmarks capture the current state of a report, allowing users to save specific views or navigate between multiple insights. For example, theyβre beneficial for storytelling or for guiding end-users through specific insights during presentations, providing an interactive experience that highlights key analysis areas.
- How can you differentiate between Related and Lookupvalue DAX functions?
Answer – RELATED retrieves values from a related table within an established relationship, making it useful for summarizing related data. LOOKUPVALUE, on the other hand, allows you to retrieve a value based on specific criteria without a direct relationship, providing flexibility when custom criteria are involved.
- How can you change the order of values displayed on the X-axis of a Column chart as per the requirement?
Answer – To customize the X-axis order in a Column chart, create a custom sorting column based on your desired sequence. Then, set this new column as the sorting reference, enabling you to display the axis in a preferred order, such as by specific categories or time sequences.
- Explain the use of UserPrincipalName() DAX function.
Answer – The UserPrincipalName() DAX function retrieves the currently logged-in userβs email or username. Itβs often used in row-level security to dynamically filter data, displaying only relevant information to each user based on their login, thus enhancing data security and user experience.
- How do you actually share your report with end-users?
Answer – Reports can be shared via Power BI Service by publishing to shared workspaces, creating apps, or through direct embedding in Microsoft Teams or SharePoint. End-users can interact with reports securely, depending on their access levels, enabling easy collaboration and data-driven decision-making across teams.
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