I'm using Postgres 9.1. The following query does not work as expected. Coalesce should return the first non-null value. However, this query returns null (1?) instead of the date (2).

select COALESCE(
    TO_DATE('','yyyymmdd'), --(1)
    TO_DATE('20130201','yyyymmdd') --(2)
    );

--(1) this evaluates independently to null
--(2) this evaluates independently to the date,
      and therefore is the first non-null value

What am I doing wrong? Any workaround?

Edit: This may have nothing to do with Coalesce at all. I tried some experiments with Case When constructs; it turns out, Postgres has this big ugly bug where it treats TO_DATE('','yyyymmdd') as not null, even though selecting it returns null.