I had an interview recently, question was like : On update trigger a validation rule to check if entered amount is greater than zero.
I answered, we can achieve it by using ischanged formula field along with checking amount < 0 condition.
But interviewer said its not an apt solution, rather IsChanged, he said to use IsNew formula equal false + amount < 0 would be the solution.
But why not IsNew considered as a solution. Is my doubt????