This is what I understood (s)he means Scenario: Laptop's price is initially $800 and then increases to $850 before dropping to $825 Design 1: with columns Am

This is what I understood (s)he means Scenario: Laptop's price is initially $800 and then increases to $850 before dropping to $825 Design 1: with columns Amount and Kind will just have a single row which will get modified with the latest value Design 2: Will have 3 rows in the above case Difference | Kind | Time stamp 800 | 'Laptop' | ts 1 +50 | 'Laptop' | ts 2 -25 | 'Laptop' | ts 3 So this latter design has 'undo' builtin edit: formating