perform basic calculations

Hey,
I am new to PHPmaker I need help, I have created a table called Items with (id, name, quantity) and another called Add with (id, Quantity, remarks). I have linked these tables, Items is a parent and Add is a child. Say Item has got (id->1, name->fork and quantity->3) and I add s new record in Add (quantity->3 and remarks->to increment this item). When that new record is added i want it to increment like add to the existing record of quantity in Items table. How do I do please?Thanks in advance,

You may use Row_Inserting or Row_Inserted event (see the topic Server Events and Client Scripts in help file) to execute an UPDATE statement.