using characteristic in "if condition" in Bex Query

In Bex Query while creating formula( local) in colomn section. i have to use characteristic in "if" condition. for example: characteristic 0plant( of char string type) has three values ZV, ND and PD. if oplant has value ZV then calculation 1, if equals ND then calculation 2 and if equals PD then no reporting. please suggest any method.

--Saurabh Tiwari