Aggregations As Measures

A common mistake in DAX is using aggregators like SUM in calculated columns instead of measures. Don't do that! It will return the same number on every row because calculated columns are row-by-row, not a single value for the whole table.

This means:

• It doesn't respond to filters.

• It takes up storage in your model.

• It behaves incorrectly in visuals.

Instead, use a measure for aggregations! A measure is a single value that recalculates dynamically based on the current filter context. This means it:

• Changes when you slice by date, customer, or product

• Returns different values depending on the visual

• Uses no extra storage

• Reflects how much was sold in the filtered context