请教一个简单的问题?
if not lb_sign then
if trim(ls_sign_result_string) = '' then
ls_sign_result_string = fill('0',256)
else
ls_sign_result_addstring = fill('0',216)
ls_sign_result_string = ls_sign_result_string + ls_sign_result_addstring
end if
怎样才能判断if trim(ls_sign_result_string) = '' 不成功,就执行else语句
而不是if not lb_sign不成功,就执行else语句