How to perform query tasks on the Power BI desktop? Power BI interview questions and answers 298

 How to perform query tasks on the Power BI desktop?

Here's a guide on performing query tasks in Power BI Desktop:

1. Access Power Query Editor:

• Home tab: Click "Transform data" to open the Power Query Editor.

• Right-click query: In the Queries pane, right-click on a query and choose "Edit query".

2. Apply Transformations:

• Transform tab: Contains a wide range of transformations to shape and clean your data.

• Common transformations:

• Rename columns: Double-click on column headers to rename.

• Remove columns: Right-click on a column and choose "Remove".

• Change data types: Select a column, go to the "Home" tab, and choose the appropriate data type.

• Filter rows: Click the filter icon on a column header and apply conditions.

• Sort data: Click the sort icon on a column header to sort ascending or descending.

3. Shape Data:

• Remove duplicates: Go to the "Remove Rows" tab and choose "Remove Duplicates".

• Split columns: Use options like "By delimiter" or "By number of characters" to split columns.

• Merge columns: Use the "Merge Columns" or "Append Queries" options to combine data.

• Pivot data: Use the "Pivot Column" or "Unpivot Columns" options to reshape data.

4. Manage Relationships:

• Manage Relationships: Click this button in the Home tab to view and manage relationships between tables.

• Create relationships: Drag a field from one table to a related field in another table to create a relationship.

5. Apply Advanced Transformations:

• Custom formulas: Use the "Add Column" tab to create custom columns with formulas and expressions.

• Conditional logic: Use the "Conditional Column" option to create columns based on conditions.

• Group and aggregate: Use the "Group By" option to create summary tables.

6. Load Data:

• Once satisfied: Click "Close & Apply" to load the transformed data into the Power BI model.

Additional Tips:

• Preview data: Use the preview pane to visualize changes as you apply transformations.

• Document steps: Use the "Applied Steps" pane to track and manage your query steps.

• Optimize performance: Consider query folding and data modeling for efficient data processing.

• Best practices: Explore online resources and tutorials for more advanced query techniques.

Power Query Editor provides a powerful and versatile environment for shaping and preparing your data before building visualizations in Power BI. By mastering its features, you can ensure the quality and accuracy of your data analysis.