Join 3 tables - Oracle native outer join v.s. ANSI outer join

select t1.id t1_id, t2.id t2_id, t3.id t3_id
from t1,t2,t3
where t1.id = t2.id(+)
and t2.id = t3.id(+)
--order by 1
;

     T1_ID      T2_ID      T3_ID

---------- ---------- ----------

         1          1          1

         3                      

         2          2           

select t1.id t1_id, t2.id t2_id, t3.id t3_id

from t1

left join t2 on t1.id = t2.id

left join t3 on t3.id = t2.id

--order by 1

;

     T1_ID      T2_ID      T3_ID

---------- ---------- ----------

         1          1          1

         3                      

         2          2           

Observation: They return same result.

Fyi,  init testing data.

drop table t1 purge;

drop table t2 purge;

drop table t3 purge;

create table t1 (id number);

create table t2 (id number);

create table t3 (id number);

insert into t1(id) select rownum from dual connect by level <= 3;

insert into t2(id) select rownum from dual connect by level <= 2;

insert into t3(id) select rownum from dual connect by level <= 1;

commit;