drop table if exists tbl1;
create table tbl1
(
patnum largeint not null,
primary key(patnum asc)
);
insert into tbl1 values (111);
insert into tbl1 values (222);
insert into tbl1 values (333);
insert into tbl1 values (444);
insert into tbl1 values (555);
insert into tbl1 values (666);

drop table if exists tbl2;
create table tbl2
(
patnum largeint not null,
primary key(patnum asc)
);
insert into tbl2 values (111);
insert into tbl2 values (222);
insert into tbl2 values (333);
insert into tbl2 values (444);
insert into tbl2 values (555);
insert into tbl2 values (666);
insert into tbl2 values (1111);
insert into tbl2 values (2222);
insert into tbl2 values (3333);

drop table if exists tbl3;
create table tbl3
(
patnum largeint not null,
primary key(patnum asc)
);
insert into tbl3 values (111);
insert into tbl3 values (222);
insert into tbl3 values (333);
insert into tbl3 values (444);
insert into tbl3 values (555);
insert into tbl3 values (666);
insert into tbl3 values (4444);
insert into tbl3 values (5555);
insert into tbl3 values (6666);

select patnum into t123 from tbl1
intersect
select patnum from tbl2
intersect
select patnum from tbl3;

select patnum into t321 from tbl3
intersect
select patnum from tbl2
intersect
select patnum from tbl1;

select patnum into t213 from tbl2
intersect
select patnum from tbl1
intersect
select patnum from tbl3;