在更新其他字段时，判断使用的字段值是否大于0
update HJY_JSJG set dwzke = case when dwdj>0 then (wlcgj-dwdj)-dwfl1-dwywf+cgjflbl*wlcgj+sljflbl*wllsj+dwfl
case when dwdj>0 then (wlcgj-dwdj)-dwfl1-dwywf+cgjflbl*wlcgj+sljflbl*wllsj+dwfl else 0 end