Finding rows that don't contain numeric data in Oracle

Question

I am trying to locate some problematic records in a very large Oracle table. The column should contain all numeric data even though it is a varchar2 column. I need to find

Answer 1

You can use this one check:

create or replace function to_n(c varchar2) return number is
begin return to_number(c);
exception when others then return -123456;
end;

select id, n from t where to_n(n) = -123456;