Question

I’d like to be able to set add a field that answers the question “For a value in this record, does that value meet some condition in another table?”. I thought I’d try a case-when with an exists, but Teradata (my dbms) does not like it. Any recommendations?

select foo,
   (case when exists (select x.foo
                      from somedb x
                      where x.bar > 0)
    then '1' else '0' end) as MyFlag

from mydb

Answer 1

I couldn’t come up with a solution that was easy to read (key when you’re dim-witted as I am), so I did a union into a temporary table:

create multiset table someDb.NiceFlags as
(
    select t.foo,
           '1' as myFlag
    from someDb.pos_txn_mstr t
    where exists(select x...)

  union all

    select t.foo,
           '0' as myFlag
    from someDb.pos_txn_mstr t
    where not exists(select x...)

) with data primary index(foo)

But now I don’t feel like a tough guy 🙁