fetching data by joining 2 tables in a view - response (12) by ulrich

Ok, in this case it is too big to transform it into a SQL UDF.
You facing here the problem of an de-normalized design which leads to komplex queries.

CREATE MULTISET TABLE DB_TEST.T1
(
A DECIMAL(15,0),
B DECIMAL(15,0),
column_position byteint,
JOINkey INTEGER,
NO INTEGER
insert_dt DATE FORMAT 'YY/MM/DD')
PRIMARY INDEX ( A );

(where column_position (e.g. 1 to 4 based on your odering) would only be needed if it has a real meaning for you)
would be a straight forward input for your mapping as you could straight forward join the two tables.
If afterwards a de-normalized presentation of the data would be required you could "aggregate" the data by doing 

Seletc t1.a, 
       t1.b, 
       max(case when column_position = 1 then t2.newfiled else null end) as nf1,
       max(case when column_position = 2 then t2.newfiled else null end) as nf2,
       max(case when column_position = 3 then t2.newfiled else null end) as nf3,
       max(case when column_position = 4 then t2.newfiled else null end) as nf4
from t1 
     left outer join 
     t2
        on t1.joinkey = t2.a
           and t2.no = t2.b
group by t1.a,
         t2.a
;

Still not most elegant SQL but performance wise it should be much more efficient then doing so many left outer joins.