--Heiko Hommes
--Case Abfrage im PLSQL

select jahr,
       (case 
        when bons between 0 and 50 then 'a) <=50'
        when bons between 51 and 100 then 'b) >50 <=100'
        when bons between 101 and 150 then 'c) >100 <=150'
        when bons between 151 and 200 then 'd) >150 <=200'
        else
        'e )>200'
       end) ums_staff
from
........

oder

select 
	(CASE Feld_num
        WHEN 1 THEN 'txt1'
        WHEN 2 THEN 'txt2'
        WHEN 3 THEN 'txt3'
        WHEN 4 THEN 'txt4'
	END)
from
.......