Daily DAX : Day 124 ALL

 Power BI DAX Function: ALL

Function Description: The ALL function in Data Analysis Expressions (DAX) for Power BI is used to remove filters from one or more columns or tables. It essentially returns all the rows in a table, ignoring any filters that might be applied at the time. Here's how it works:

• Syntax: ALL([TableNameOrColumn], [ColumnName1], [ColumnName2], ...)
  
  
  • If you specify a table, ALL returns all rows from that table.
  • If you specify column names, it returns all unique values from those columns, regardless of any filter context in effect.

Parameters:

• TableNameOrColumn: Can be a table or a column from which you want to remove filters.
• ColumnName: Optional, you can specify multiple columns if you're removing filters from specific columns within a table.

Key Points:

• ALL can be used with tables, columns, or both within the same function call.
• When used with tables, it removes all filters on that table.
• When used with columns, it removes filters only on those specified columns.

Use Cases:

1. Total Sales Calculation:
   • You might want to calculate total sales across all dates when you're currently filtering by a specific date range. Here's how you'd use ALL:
     
     
     DAX

     Total Sales = CALCULATE(SUM(Sales[Amount]), ALL(Dates))

     
     
     This measure would return the total sales for all dates, regardless of any date filter applied in the report.
2. Percentage of Total:
   • When calculating percentages where you need the total across all categories, ALL can be crucial:
     
     
     DAX

     Sales Percentage = 
     DIVIDE(
       SUM(Sales[Amount]),
       CALCULATE(SUM(Sales[Amount]), ALL(Sales[Category]))
     )

   
   
   Here, it calculates the percentage of sales for each category compared to the total sales of all categories.
3. Resetting Context for Measures:
   • Sometimes, you need to reset the context for a part of your calculation. For example, if you're calculating a running total but want the denominator to be the total across all rows:
     
     
     DAX

     Running Total Percentage = 
     DIVIDE(
       [Running Total],
       CALCULATE([Running Total], ALL(DateTable[Date]))
     )

4. Time Intelligence:
   • ALL is often used in time intelligence calculations where you might want to compare current data with historical data across all time periods:
     
     
     DAX

     Sales Growth = 
     DIVIDE(
       SUM(Sales[Amount]) - CALCULATE(SUM(Sales[Amount]), ALL(DateTable[Date])),
       CALCULATE(SUM(Sales[Amount]), ALL(DateTable[Date]))
     )

Important Note:

• Be cautious with ALL as it can significantly increase the computational load if you're dealing with large datasets, since it's essentially re-evaluating the measure over all rows.

By using ALL, you can manipulate the filter context in DAX calculations to achieve complex analytical insights in Power BI. Remember, the effectiveness of ALL largely depends on your understanding of the filter context in DAX.