Dynamics 365 has built in functionality for calculated fields. These are fields that can be set up without code. Here we will go through an example.
Let’s assume we need a new calculated field on the Order entity. Let’s create a new field. Enter the display name and select the data type. Now select the field type. You can see here there are the options:
Note, not all of these field types are available for all data types.
Select Calculated. We now see an Edit button.
You will see the calculation window open:
You can add a condition, which is optional:
And an Action:
As a simple example, let’s add the total amount to itself:
Save the field and open the form. We will add the field to the form:
Save and publish the form.
Displaying a previous order, you will see the new calculated field and its value:
More information on the functions available can be found here: https://technet.microsoft.com/en-us/library/dn832103.aspx
This link also discusses some of the limitations in using calculated fields, such as this feature not working in Outlook Offline mode.