Robert is right. The easiest Mendix way is a retrieve and loop in a microflow. There is a way however that will give you better performance if need be, and that is OQL. You do a retrieve over the person, select avg((datediff(DAY,dateofbirth, currentdate)) like this:
FROM ForumQuestions.Employee SELECT avg(datediff(DAY, DateOfBirth, '[%CurrentDateTime%]')) as AverageDaysOfOurPersons
And this is also very doable. To use this OQL:
See https://forumquestions-sandbox.mxapps.io/p/questions, click question 96873 for a working sample. and click on the pencil on right side of the screen to view it in Studio (Awesome feature in this usecase). It actually was easier to accomplish then I expected.
Nevertheless, you also want to know how to do this in a microflow and loop, see this shared microflow as example:
The easiest way to do this would be to retrieve all the users and loop over them. You would need to calculate each age in the loop, then add to a total combined age. Outside the loop you would then divide this by the total number of users to get the average (mean) age.
Hope this helps.
Thanks for the answers, i need to use microflow for this, i know how to retrieve a list of the users inside the microflow but i am not sure how to calculate the age in the loop.
Thanks for your help.