>>> "Scott Whitney" <swhitney@xxxxxxxxxxx> wrote:
> Um. How is this possible?
> mydb=# select * from time_recs where id_time_rec not in (select
> id_time_rec from punch_time_recs);
> (0 rows)
> Table "public.punch_time_recs"
> Column | Type | Modifiers
>
-------------------+------------------------+-------------------------------
> id_time_rec | character varying(38) |
The column in punch_time_recs is null capable. Try using NOT EXISTS.
The SQL spec requires the NOT IN to be the equivalent of a "not
equals" test for all entries, and you can't say that any given value
is not equal to NULL, since NULL can mean that there is a value but
you don't know it. The semantics of NOT EXISTS are subtly different
here -- it means there aren't any rows known to have the value.
-Kevin
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