PostgreSQL 表之間連接測試

create table if not EXISTS atmp(oid int8 PRIMARY key);
INSERT into atmp values(1) on conflict(oid) do update set OID = 1;
INSERT into atmp values(2) on conflict(oid) do update set OID = 2;
INSERT into atmp values(3) on conflict(oid) do update set OID = 3;
INSERT into atmp values(1) on conflict(oid) do update set OID = 1;

create table if not EXISTS atmp2(oid int8 PRIMARY key);
INSERT into atmp2 values(1) on conflict(oid) do update set OID = 1;
INSERT into atmp2 values(4) on conflict(oid) do update set OID = 4;
create table if not EXISTS atmpret(oid int8 PRIMARY key);

select  * from atmp natural join atmp2;
select  * from atmp as a inner join atmp2 as b  on a.oid = b.oid ;
select  * from atmp as a left join atmp2 as b  on a.oid = b.oid ;
select  * from atmp as a full join atmp2 as b  on a.oid = b.oid ;
select  * from atmp as a right join atmp2 as b  on a.oid = b.oid ;
select  * from atmp as a  join atmp2 as b  on a.oid = b.oid ;