Oracle "create table as" null value

Question

If you create an Oracle table using "create as" where one of your fields is null you will get the error:

ORA-01723: zero-length columns are not allowed

Example query:

create table mytable as 
select 
    field_a, 
    null brand_new_field
from anothertable;

How can you get around this?

Answer 1

Figured it out need to use cast(null as datatype)

create table mytable as 
select 
    field_a, 
    cast(null as varchar(1)) brand_new_field
from anothertable;

Some more info here.