>>> "Scott Whitney" <swhit...@journyx.com> 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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