Re: Most efficient SQL approach

Thanks... I just thought it was me.

I created 5 CTEs for each of the columns I needed... it was relatively
slow in ACS. Anxious to see how fast it runs in an RPG pgm in batch.



-----Original Message-----
From: RPG400-L [mailto:rpg400-l-bounces@xxxxxxxxxxxxxxxxxx] On Behalf Of
Charles Wilt
Sent: Friday, March 06, 2020 5:00 PM
To: RPG programming on IBM i <rpg400-l@xxxxxxxxxxxxxxxxxx>
Subject: Re: Most efficient SQL approach

I can't think of anything off-hand...

The grouping/rollup/cube functions are nice for YTD, MTD, WTD stuff...

But for YTD and Prior-YTD, the individual CTEs (or views) are likely the
best bet...

Charles

On Fri, Mar 6, 2020 at 2:04 PM Greg Wilburn <
gwilburn@xxxxxxxxxxxxxxxxxxxxxxx> wrote:

I'm not sure I understand how OLAP functions fit in.

If I could get one CTE with Order totals current year-to-date and

previous

year-to-date by customer, and the same for Invoice Total by customer

-----Original Message-----
From: RPG400-L [mailto:rpg400-l-bounces@xxxxxxxxxxxxxxxxxx] On Behalf Of
Birgitta Hauser
Sent: Friday, March 06, 2020 1:04 PM
To: 'RPG programming on IBM i' <rpg400-l@xxxxxxxxxxxxxxxxxx>
Subject: RE: Most efficient SQL approach

I'd use Common Tables Expressions in composition with OLAP Functions

Mit freundlichen Grüßen / Best regards

Birgitta Hauser


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-----Original Message-----
From: RPG400-L <rpg400-l-bounces@xxxxxxxxxxxxxxxxxx> On Behalf Of Greg
Wilburn
Sent: Freitag, 6. März 2020 17:52
To: RPG programming on IBM i <rpg400-l@xxxxxxxxxxxxxxxxxx>
Subject: Most efficient SQL approach

I am rewriting an old RPG report using SQL (and SQL views I already

have).

The "report" generates a database table as output

I need one row for each customer. In each row I need columns for several
sales figures that can be found in two other views.
I have SQL views for the Customer, Invoices and Orders.

I currently have it written where each sales figure is a separate
sub-select. Note that the "where" clause for each is slightly different.

It seems like this could be written more efficiently... but I'm not sure
what approach to take

1. Use common table expressions?

2. Create the output table, then use separate SQL expressions to
insert
each of the summed values?

This is a simplified version of the code (for simplicity I've replaced

the

RPG variables with constant values).

SELECT CUS.COM_NBR, CUS.CUST_NBR, CUS.CUST_NAME, (more here), (select
coalesce(sum(opn_amt),0) from V_ORDERS where com_nbr=cus.com_nbr and
ent_nbr=cus.ent_nbr and
ord_date>='2020-01-01' and ord_date<='2020-03-04') as BOOK_YTD,
(select coalesce(sum(shp_amt),0) from V_INVOICES where

com_nbr=cus.com_nbr

and ent_nbr=cus.ent_nbr and
inv_date>='2020-01-01' and inv_date<='2020-03-04' )as NET_YTD,
(select coalesce(sum(shp_amt),0) from V_INVOICES where

com_nbr=cus.com_nbr

and ent_nbr=cus.ent_nbr and
inv_date>='2019-01-01' and inv_date<='2019-03-04' ) as
PREV_YR_TOTAL, (select coalesce(sum(shp_amt),0) from V_INVOICES where
com_nbr=cus.com_nbr and ent_nbr=cus.ent_nbr and
inv_date>='2019-01-01' and inv_date<='2019-03-04' ) as
NET_PREV_YTD, (select coalesce(sum(ord_amt),0) from V_ORDERSA where
com_nbr=cus.com_nbr and ent_nbr=cus.ent_nbr and
ord_date>='2019-01-01' and ord_date<='2019-03-04') as
BOOK_PREV_YTD
from V_CUSTMSTR as CUS where CUS.COM_NBR='012';

Thanks,
Greg
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