I agree with @Jonathan_S request.
What @Marc_Dillon suggests with “execute an action on a set of rows” does not directly solve the needed problem without extra complexity added.
Consider the common problem of updating Inventory from Order Details.
I can create a Workflow that detects when an Order is completed and then use an “execute an action on a set of rows” to get the list of Product Codes and call another action to update the associated Inventory records by those Product Codes.
The problem is when I am in the Action to update the Inventory, all I have is the Product Code from the Order Detail record. I have no way to link back to the precise Order Detail record that holds the Quantity that needs to be adjusted on the Inventory record.
We are left with creating some kind of workaround method to deal with this gap.
If there was an “update a row in another table using values from this row” Action, then we can directly make the Inventory update with no added complexity needed.
I recognize that in a multi-user distributed system, this may not be the best approach. But there are many instances for developers where this would be sufficient. AppSheet platform should just give the tools and, being a no-code/low-code system, the tools should be easy to use. It is up to the developer to make sure they are using the RIGHT tool for the apps needs.