Question

How can I unpivot multiple columns dynamically while keeping other columns unchanged in Power Query?
I need to transform a dataset by unpivoting multiple columns dynamically in Power Query while ensuring that some key columns remain unchanged. What is the best way to achieve this efficiently?

Answer 1

To dynamically unpivot multiple columns in Power Query while keeping key columns unchanged, follow these steps:

1. Identify Key and Unpivot Columns

 Select Key Columns – These are the columns that should remain unchanged (e.g., Date, Category).
Dynamically Select Columns to Unpivot – Instead of hardcoding, use Table.ColumnNames() to determine which columns need unpivoting dynamically.

2. Use Power Query M Code for Dynamic Unpivoting

let
    Source = YourTable,  
    KeyColumns = {"Date", "Category"},  // Adjust with your key columns  
    AllColumns = Table.ColumnNames(Source),  
    UnpivotColumns = List.Difference(AllColumns, KeyColumns),  
    UnpivotedTable = Table.UnpivotOtherColumns(Source, KeyColumns, "Attribute", "Value")  
in  
    UnpivotedTable

 List.Difference(AllColumns, KeyColumns) ensures that only the required columns are unpivoted, even if new columns are added later.
 Table.UnpivotOtherColumns() efficiently transforms the dataset without manually selecting columns.

3. Optimize for Performance

 Remove Unnecessary Columns before unpivoting to reduce data processing overhead.
 Apply Filtering Early in Power Query to minimize the number of rows processed.