Outer Join Sequence Priority

Question

Hi,
I have a select statement like this:
SELECT *
FROM
T1
INNER JOIN T2 ON T1.ID=T2.ID
LEFT OUTER JOIN T3 ON T2.ID=T3.ID
The problem is I need the query processor LEFT JOIN T2 and T3, then, INNER
JOIN the result with T1.
I tried to use bracket like this:
SELECT *
FROM
T1
INNER JOIN T2 ON T1.ID=T2.ID
LEFT OUTER JOIN T3 ON T1.ID=T2.ID
But it gives me error. Is there any way that I enforce the sequence of the
join priority?
Any help would be appreciated,
Alan

Answer 1

I really don't think the join order will affect your results. The bottom line is that T1 will drive the results.
SQL>  select /*+ ORDERED */ t1.id t1id, t2.id t2id, t3.id t3id
  2  from t1 inner join t2 on t1.id = t2.id
  3* left join t3 on t2.id = t3.id;
<BR><BR>
      T1ID       T2ID       T3ID
         1          1          1
         2          2
<BR><BR>
Execution Plan
   0      SELECT STATEMENT Optimizer=CHOOSE (Cost=8 Card=5 Bytes=30)
   1    0   HASH JOIN (OUTER) (Cost=8 Card=5 Bytes=30)
   2    1     HASH JOIN (Cost=5 Card=5 Bytes=20)
   3    2       TABLE ACCESS (FULL) OF 'T1' (Cost=2 Card=5 Bytes=10)
   4    2       TABLE ACCESS (FULL) OF 'T2' (Cost=2 Card=9 Bytes=18)
   5    1     TABLE ACCESS (FULL) OF 'T3' (Cost=2 Card=5 Bytes=10)
<BR><BR><BR>
SQL>  select /*+ ORDERED */ t1.id t1id, t2.id t2id, t3.id t3id
  2  from t2 left join t3 on t2.id = t3.id
  3* inner join t1 on t1.id = t2.id
<BR><BR>
      T1ID       T2ID       T3ID
         1          1          1
         2          2
<BR><BR>
Execution Plan
   0      SELECT STATEMENT Optimizer=CHOOSE (Cost=8 Card=5 Bytes=30)
   1    0   HASH JOIN (Cost=8 Card=5 Bytes=30)
   2    1     HASH JOIN (OUTER) (Cost=5 Card=9 Bytes=36)
   3    2       TABLE ACCESS (FULL) OF 'T2' (Cost=2 Card=9 Bytes=18)
   4    2       TABLE ACCESS (FULL) OF 'T3' (Cost=2 Card=5 Bytes=10)
   5    1     TABLE ACCESS (FULL) OF 'T1' (Cost=2 Card=5 Bytes=10)