# Calculated columns

You can get more information about the data by making calculations based on the existing data columns in the data table. A calculation can contain mathematical as well as logical expressions. One way to expose the results from a calculation is to add them as values into a new data column.

Generally the calculation of the new data column is a once-only calculation. This means that once a value is calculated, it is definitive and will not change upon filtering. If the data is refreshed, though, a recalculation of the values takes place.

## Writing expressions

How to add the results into a new data column is described in Adding a calculated column. When you specify what to calculate, you can use various aggregation methods like sum or average to group data by, and you base the calculation on the existing data columns.

To make the expressions interpretable, you must use a certain syntax. For information about the syntax, see Expression language details. Depending on how the expression for the calculated column is set up, it is evaluated across each row in the data table, or down an entire column.

If you later on want to see or edit the details of the expression used for calculating the column values, you select the column in the Data in analysis flyout and expand the flyout to view Details on selected column. See Editing a calculated column. In addition, information about the added column is available in the Data canvas.