getting data from table with nearest date

I want to create a query where any null values IN val COLUMN in table1
are replaced with value from table2 (VAL column) where the rules are:
join tabkle1 to table2 re: ID1 & ID2 and the value retuned from table2 (column VAL)
must be the row where the date in table2 is either equal or next date back
from that in table1 - see output table for desired result

Company       ID1      ID2     DATE          VAL
abc            123      1       01/03/2008     34
def            124      11      01/03/2009     NULL

ID1      ID2     DATE          VAL
123      1       01/03/2008     34
124      11      01/02/2004     50
124      11      01/02/2008     67
124      11      01/02/2011     12

SQL query required to produce ..............
cpy       ID1      ID2     DATE          VAL
abc      123      1       01/03/2008     34
def      124      11      01/03/2009     67 -- date returned from table1 and val 67
                                 -- is nearest date in table2 <= table1 date
Who is Participating?
SELECT company,
       NVL(val, val2)
  FROM (SELECT t1.*,
               t2.val val2,
               ROW_NUMBER() OVER (PARTITION BY t1.id1, t1.id2 ORDER BY t1.d - t2.d) rn
          FROM table1 t1, table2 t2
         WHERE t1.id1 = t2.id1 AND t1.id2 = t2.id2 AND t2.d <= t1.d)
 WHERE rn = 1
philsivyerAuthor Commented:
Thanks for this
philsivyerAuthor Commented:
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