Measure DAX
Numeric columns support the greatest range of aggregation functions:
- Sum
- Average
- Minimum
- Maximum
- Count (Distinct)
- Count
- Standard deviation
- Variance
- Median
Summarize non-numeric columns
Non-numeric columns can be summarized. However, the sigma symbol does not show next to non-numeric columns in the Fields pane because they don't summarize by default.
Text columns allow the following aggregations:
- First (alphabetically)
- Last (alphabetically)
- Count (Distinct)
- Count
Date columns allow the following aggregations:
- Earliest
- Latest
- Count (Distinct)
- Count
Boolean columns allow the following aggregations:
- Count (Distinct)
- Count
Compare calculated columns with measures
100 XP
DAX beginners often experience a degree of confusion about calculated columns and measures. The following section reviews the similarities and differences between both.
Regarding similarities between calculated columns and measures, both are:
- Calculations that you can add to your data model.
- Defined by using a DAX formula.
- Referenced in DAX formulas by enclosing their names within square brackets.
The areas where calculated columns and measures differ include:
- Purpose - Calculated columns extend a table with a new column, while measures define how to summarize model data.
- Evaluation - Calculated columns are evaluated by using row context at data refresh time, while measures are evaluated by using filter context at query time. Filter context is introduced in a later module; it's an important topic to understand and master so that you can achieve complex summarizations.
- Storage - Calculated columns (in Import storage mode tables) store a value for each row in the table, but a measure never stores values in the model.
- Visual use - Calculated columns (like any column) can be used to filter, group, or summarize (as an implicit measure), whereas measures are designed to summarize.
No comments:
Post a Comment