Tableau does not have dynamic parameters and hence it is not possible to change the values of these parameters on the fly. Instead, you can opt for calculated field as below and then base your calculations on top of it.
IF Percent Increase == 0 AND Amount Increase == 0 THEN "Error Message 1"
ELSEIF Percent Increase <> 0 AND Amount Increase <> 0 THEN "Error Message 2"
Hope this helps.
Please see the below cal hope it helps you.
IF ATTR([Percent Increase]) = 0 then [Amount Increase] != 0 elseif ATTR([Percent Increase]) != 0 then [Amount Increase] = 0 END
Thank you. But how do I display the error message? I do not want to change parameters on the fly. Just display an error message so that the user can go back and correct.