Oracle 18c

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CREATE TABLE a (id, id1, id2) AS
SELECT 1, 1, 1 FROM DUAL UNION ALL
SELECT 2, 2, 2 FROM DUAL UNION ALL
SELECT 3, 3, 3 FROM DUAL UNION ALL
SELECT 4, 4, 4 FROM DUAL;
4 rows affected

CREATE TABLE b (id, xxx) AS
SELECT 1, 1 FROM DUAL UNION ALL
SELECT 2, 2 FROM DUAL;
2 rows affected

CREATE TABLE c (id, yyy) AS
SELECT 1, 1 FROM DUAL UNION ALL
SELECT 3, 3 FROM DUAL;
2 rows affected

SELECT *
FROM a, b, c
WHERE
b.id (+) = a.id1
AND b.xxx = c.yyy
AND c.id (+) = a.id2


ID
ID1
ID2
ID
XXX
ID
YYY


1
1
1
1
1
1
1


SELECT *
FROM   a
       INNER JOIN b ON (a.id1 = b.id)
       INNER JOIN c ON (a.id2 = c.id AND b.xxx = c.yyy)


ID
ID1
ID2
ID
XXX
ID
YYY


1
1
1
1
1
1
1


select *
from   A
       left outer join B on B.ID = A.ID1
       left outer join C on C.ID = A.ID2 AND B.xxx = C.yyy


ID
ID1
ID2
ID
XXX
ID
YYY


1
1
1
1
1
1
1

4
4
4
null
null
null
null

3
3
3
null
null
null
null

2
2
2
2
2
null
null


SELECT *
FROM a, b, c
WHERE b.id (+) = a.id1
AND   b.xxx = c.yyy (+)
AND   c.id (+) = a.id2


ID
ID1
ID2
ID
XXX
ID
YYY


1
1
1
1
1
1
1

4
4
4
null
null
null
null

2
2
2
2
2
null
null

3
3
3
null
null
null
null


select *
from   A
       left outer join C on C.ID = A.ID2
       left outer join B on B.ID = A.ID1 AND B.xxx = C.yyy


ID
ID1
ID2
ID
YYY
ID
XXX


1
1
1
1
1
1
1

4
4
4
null
null
null
null

3
3
3
3
3
null
null

2
2
2
null
null
null
null


SELECT *
FROM a, b, c
WHERE b.id (+) = a.id1
AND   b.xxx (+) = c.yyy
AND   c.id (+) = a.id2


ID
ID1
ID2
ID
XXX
ID
YYY


1
1
1
1
1
1
1

4
4
4
null
null
null
null

3
3
3
null
null
3
3

2
2
2
null
null
null
null


select *
from   A
       left outer join (
         SELECT b.id AS b_id,
                c.id AS c_id,
                b.xxx,
                c.yyy
         FROM   b
                INNER JOIN c ON b.xxx = c.yyy
       ) bc
       on bc.b_id = a.id1 AND bc.c_id = a.id2


ID
ID1
ID2
B_ID
C_ID
XXX
YYY


1
1
1
1
1
1
1

4
4
4
null
null
null
null

2
2
2
null
null
null
null

3
3
3
null
null
null
null


select *
from   A,
       (
         SELECT b.id AS b_id,
                c.id AS c_id,
                b.xxx,
                c.yyy
         FROM   b, c
         WHERE  b.xxx = c.yyy
       ) bc
WHERE  bc.b_id (+) = a.id1
AND    bc.c_id (+) = a.id2


ID
ID1
ID2
B_ID
C_ID
XXX
YYY


1
1
1
1
1
1
1

4
4
4
null
null
null
null

2
2
2
null
null
null
null

3
3
3
null
null
null
null


SELECT *
FROM   a
       LEFT OUTER JOIN (
         b
         INNER JOIN c
         ON b.xxx = c.yyy
       )
       ON b.id = a.id1 AND c.id = a.id2


ID
ID1
ID2
ID
XXX
ID
YYY


1
1
1
1
1
1
1

4
4
4
null
null
null
null

2
2
2
null
null
null
null

3
3
3
null
null
null
null

ID	ID1	ID2	ID	XXX	ID	YYY
1	1	1	1	1	1	1
4	4	4	null	null	null	null
3	3	3	null	null	null	null
2	2	2	2	2	null	null

ID	ID1	ID2	ID	XXX	ID	YYY
1	1	1	1	1	1	1
4	4	4	null	null	null	null
2	2	2	2	2	null	null
3	3	3	null	null	null	null

ID	ID1	ID2	ID	YYY	ID	XXX
1	1	1	1	1	1	1
4	4	4	null	null	null	null
3	3	3	3	3	null	null
2	2	2	null	null	null	null

ID	ID1	ID2	ID	XXX	ID	YYY
1	1	1	1	1	1	1
4	4	4	null	null	null	null
3	3	3	null	null	3	3
2	2	2	null	null	null	null

ID	ID1	ID2	B_ID	C_ID	XXX	YYY
1	1	1	1	1	1	1
4	4	4	null	null	null	null
2	2	2	null	null	null	null
3	3	3	null	null	null	null