drop table a;
drop table b;
create table a (a_v VARCHAR2(6 CHAR));
insert into a values (1);
insert into a values (2);
create table b (b_v VARCHAR2(6 CHAR));
insert into b values (1);

SELECT * FROM a OUTER LEFT JOIN b ON a_v = b_v;

SELECT * FROM a OUTER LEFT JOIN b ON a.a_v = b.b_v;