> For instance you could write a FSM that transitions from "paid" to "delivered"... or you could have two columns, paid_at and delivered_at, and consider those

> For instance you could write a FSM that transitions from "paid" to "delivered"... or you could have two columns, paid_at and delivered_at, and consider those two columns orthogonal. The first seems to imply that delivery cannot occur until the state 'paid' has been reached, while the second contains no such implication. Either might be correct, depending on how the business operates, and modeling the states and the allowable transitions between them is an excellent way to find out what questions need to be answered before you can produce a correct implementation - better in every way than implementing what seems right intuitively, and then seeing what happens.