在oracle中判断某个字段的值是否为数字

create or replace function Isnumber(P_column in varchar2) return number is
l_t number;
begin
l_t := to_number(P_column);
return 1;
exception
when others then
return 0;
end;

select t.pub_price, t.trade_price, t.* from travel_line t where  Isnumber(t.pub_price) = 1 and Isnumber(t.trade_price) = 1