Leon' rašė:
> sorry uz caps lock'a:
> 
> CREATE TABLE GAM_PLAN (
>     ..........,
>     KODAS CHAR (20) CHARACTER SET WIN1257 NOT NULL COLLATE WIN1257,
> ....................)
> 
> 
> CREATE TABLE PAMAINA (
>    .............,
>     KODAS CHAR (20) CHARACTER SET WIN1257 NOT NULL COLLATE WIN1257,
>    ...............)
> 

Užklausa *tikrai* tik vieną lauką paima? (nes grąžinamos unique rows, o 
ne unique fields).

Anomalija tada...
Versija?
FB 2.1 veikia korektiškai (tiesa be collate).

Testas:

create table a (id int, pav char (20));
create table b (id int, pav char (20));

insert into a (id, pav) values (1, 'zzz1');
insert into a (id, pav) values (2, 'zzz2');
insert into a (id, pav) values (3, 'zzz3');
insert into a (id, pav) values (4, 'zzz4');
insert into a (id, pav) values (5, 'zzz1');
insert into a (id, pav) values (6, 'zzz2');
insert into a (id, pav) values (7, 'zzz3');
insert into a (id, pav) values (8, 'zzz4');
insert into a (id, pav) values (9, 'AAAA');

insert into b select * from a;


update b set pav = 'zzzb2' where pav = 'zzz2';
update b set pav = 'zzzb3' where pav = 'zzz3';

select pav from a
union
select pav from b


Rezultatas:

    PAV
1  AAAA
2  zzz1
3  zzz2
4  zzz3
5  zzz4
6  zzzb2
7  zzzb3