Formula between parent and child and pull results to parent table

I have a parent table which has the

  1. project.ID,(primary key)
  2. project Budget and
  3. project remaining budget.

My child table has multiple rows of…

  1. purchase transactions and
  2. purchase costs.
    …against each project ID

I need to sum up all purchase costs and subtract it from my parent table’s project budget to get my remaining budget balance.

Any idea how to do it? I am lost, is their a setting I am missing, how do I work this equation? Any help would be appreciated.


Hello EITS,

what about if you sum up all purchase costs per project with a Sum-Field “Aggregate Purchase cost per project” in the project table. Then, you calculate the difference between “Project Budget” - “Aggregate Purchase cost per project” in a Formula field in the project table.

Is this what you are looking for?


Thank you very much. It worked!