/* Establish environment */
drop table if exists A;
drop table if exists B;
drop table if exists C;
create table A ( ID integer );
create table B ( ID integer );
create table C ( ID integer );
insert into A values(1);

drop table if exists Z;
create table Z ( ID integer );

/* Causes AV */
insert into Z
select ID from A
union 
select ID from B
union 
select ID from C