Your question is not clear enough to me, may you can give an example?
For example, you have car objects whereby color of them all is green. Now you want to change the color of all cars to red:
Create MicroFlow with:
1 - Retrieve all cars (if you want constrained to just green cars by filling in the Xpath: [color = green] from database. This is a list.
2 - Now make a loop and go over all the car objects and change the color attribute to red
3 - Commit the list of 1.