update 具体表名 set khdm = substring(khdm, 2, 3) where khdm='x001'
update 具体表名 set khdm = substring(khdm, 2, 3) where khdm='x002'
update 具体表名 set khdm = substring(khdm, 2, 3) where khdm='x003'
还有一种跟简单的、
update 具体表名 set khdm = substring(khdm, 2, 3) where khdm like 'x%'