I would use a CTE with row_number() to generate a priority sequence for the part master rows, such that priority 1 is the part with the lowest lead time and then join to the priority 1 row like this:
declare global temporary table PART_MASTER as (
select * from(values
('ABC', 1, 34),
('ABC', 2, 16),
('DEF', 1, 7),
('DEF', 2, 234)
) x(PART_NO, WHS, LEAD_TIME)
) with data with replace
;;
declare global temporary table LINE_ITEMS as (
select * from(values
(1, 'ABC'),
(2, 'DEF')
) x(LINE_NO, PART_NO)
) with data with replace
;;
with PARTS_BY_LOWEST_LEAD_TIME as (
select row_number() over(partition by PART_NO order by LEAD_TIME asc) as PRIO,
X.*
from PART_MASTER X
)
select *
from LINE_ITEMS L
join PARTS_BY_LOWEST_LEAD_TIME P
on P.PART_NO = L.PART_NO and
P.PRIO = 1
Tim.
________________________________
From: MIDRANGE-L <midrange-l-bounces@xxxxxxxxxxxxxxxxxx> on behalf of James H. H. Lampert via MIDRANGE-L <midrange-l@xxxxxxxxxxxxxxxxxx>
Sent: 03 January 2022 22:30
To: Midrange Systems Technical Discussion <midrange-l@xxxxxxxxxxxxxxxxxx>
Cc: James H. H. Lampert <jamesl@xxxxxxxxxxxxxxxxx>
Subject: SQL question
Suppose we have a line-item file, and a part master file.
The line item records have a part number. And it cross-references to the
part master file.
But if a given part is stocked in two or more warehouses, then the part
master file has a record for it at each warehouse that stocks it.
Now, suppose we have a join between the line item file and the part
master file, on the part number. For each line item, the join is
returning a record for every matching part master record.
Not especially good. Is there a way, that works in DB2/400, to limit
that to only one join record per line item? And to select, for example,
the one with the low value in the "lead time" field?
--
JHHL
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