RE: SQL: how to join header and detail records

Yes I agree MAX/MIN would work, so would AVG. But it just doesn't seem very self-documenting. If someone else were to look at it a year later, they may be steered down the thought path that the developer was trying to do something other than use the simple column value.



-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Michael Schutte
Sent: Wednesday, April 03, 2013 12:21 PM
To: Midrange Systems Technical Discussion
Subject: Re: SQL: how to join header and detail records

You would either need to MAX/MIN totqty or put it in the GROUP BY.

I would MIN or MAX, it wouldn't matter because it would return the same
value every time.


On Wed, Apr 3, 2013 at 1:09 PM, <rob@xxxxxxxxx> wrote:

The magic word is HAVING.
HAVING is to GROUP as ... well, not really a good comparison. Just let me
explain it to you

Select orderno, totqty, sum(dtlqty) as dtlsum
from orderheader join orderdetail using orderno
group by orderno
having totqty <> dtlsum

Now, you may have to say
<> sum(dtlqty)
but you should get the concept from that.


Rob Berendt
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From: "Stone, Joel" <Joel.Stone@xxxxxxxxxx>
To: "'Midrange Systems Technical Discussion'"
<midrange-l@xxxxxxxxxxxx>,
Date: 04/03/2013 12:59 PM
Subject: SQL: how to join header and detail records
Sent by: midrange-l-bounces@xxxxxxxxxxxx



I have an order header and detail file with one to many.

The order header has TOTQTY, which is the sum of all detail quantities.

The order detail has DTLQTY, which is one line's qty.



If I do a join of the two files and there is one HDR and five DTL records,
there will now be FIVE rows.

I want to compare the sum of the DTLQTY to the single TOTQTY value.

I can use SUM(DTLQTY) to provide the sum of the detail.

What is a good way to provide the TOTQTY? I don't want to use SUM(TOTQTY)
as this would give a result 5 times the correct value.

Is MAX(TOTQTY) what people generally use?

But that seems to be misleading since I am not really looking for the max
value, as all rows contain the same value for a header column.

Should I be grouping the detail PRIOR to the join, so there is only ONE
header value?

But it seems like the SQL stmt is SO much simpler if I do the join first.

Any ideas?

Thanks!



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