SQL AS/400 - Extract product price per store - sql

Question

We have a phone dialer who call us store to inform them about gas price in their region.
We have 3 tables (WBDAPP00,WBDCIE00,WBDCIA00)
WBDAPP00 is where we store information about the call.
DANOID = ID
DA#INT,DA#IND,DA#TEL = phone number
DA#ENV = The number of group call, we send 1 message to few store.
DASTAT = The status of the call (Confirm by store,canceled,running, confirmed by us, in pause)
DADTHR = The timestamp of the last status modification
WBDCIE00 is where we store information about the group of store
CIE#EN = ID
CIEDHC = The timestamp where the call is effective, we can call the morning to tell the price will change at 14h30
CIE$OR = The price for regular
CIE$PL = The price for plus
CIE$SP = The price for super
CIE$DI = The price for diesel
WBDCIA00 is complementary information about WBDAPP00
CIA#ST = The ID of the store
CIA#AP = The ID of the call
CIE#EN = The ID of the group call
CIABAN = This is the number of the compagny of the store
This is a sample output of these 3 tables
SELECT * FROM PRDCM/WBDAPP00 WHERE DA#ENV = 17258 OR DA#ENV = 17257
+--------+--------+--------+---------+--------+--------+----------------------------+-----------+--------+
| DANOID | DA#INT | DA#IND | DA#TEL | DA#ENV | DASTAT | DADTHR | DAPARM | DAMUSR |
+--------+--------+--------+---------+--------+--------+----------------------------+-----------+--------+
| 100420 | 1 | 418 | 9600055 | 17257 | 4 | 2012-05-07-09.15.04.768228 |1;2;1;1;1;1| ISALAP |
| 100421 | 1 | 819 | 7346491 | 17258 | 0 | 2012-05-07-09.23.32.362971 |0;4;0;1;0;0| ISALAP |
| 100422 | 1 | 819 | 7624747 | 17258 | 1 | 2012-05-07-09.24.28.042330 |0;3;1;1;0;1| ISALAP |
| 100423 | 1 | 819 | 6377874 | 17258 | 0 | 2012-05-07-09.23.32.803073 |0;3;0;1;0;1| ISALAP |
| 100424 | 1 | 819 | 8742844 | 17258 | 1 | 2012-05-07-09.24.25.347116 |1;1;1;1;0;1| ISALAP |
| 100425 | 1 | 819 | 8255744 | 17258 | 0 | 2012-05-07-09.23.33.207688 |1;3;1;1;0;1| ISALAP |
+--------+--------+--------+---------+--------+--------+----------------------------+-----------+--------+
SELECT * FROM PRDCM/WBDCIE00 WHERE CIE#EN = 17258 OR CIE#EN = 17257
+--------+----------------------------+--------+--------+--------+--------+
| CIE#EN | CIEDHC | CIE$OR | CIE$PL | CIE$SP | CIE$DI |
+--------+----------------------------+--------+--------+--------+--------+
| 17257 | 2012-05-04-17.00.00.000000 | 0 | 0 | 0 | 1,359 |
| 17258 | 2012-05-07-09.30.00.000000 | 1,354 | 0 | 0 | 0 |
+--------+----------------------------+--------+--------+--------+--------+
SELECT * FROM PRDCM/WBDCIA00 WHERE CIA#EN = 17258 OR CIA#EN = 17257
+--------+--------+--------+--------+
| CIA#ST | CIA#AP | CIA#EN | CIABAN |
+--------+--------+--------+--------+
| 96 | 100420 | 17257 | 2 |
| 316 | 100421 | 17258 | 4 |
| 320 | 100422 | 17258 | 3 |
| 321 | 100423 | 17258 | 3 |
| 338 | 100424 | 17258 | 1 |
| 366 | 100425 | 17258 | 3 |
+--------+--------+--------+--------+
This is the relation between tables
CIA#AP = DANOID
CIA#EN = CIE#EN = DA#ENV
I want to extract the last CIE$OR (not 0) and the last CIE$DI (not 0) for each CIA#ST.
The last one is determined by CIEDHC (Desc order).
DASTAT needs to be 1 or 4.
This is an example of want I want to extract from the data above :
+--------+--------+--------+
| CIA#ST | CIE$OR | CIE$DI |
+--------+--------+--------+
| 96 | 0 | 1,359 |
| 316 | 1,354 | 0 |
| 320 | 1,354 | 0 |
| 321 | 1,354 | 0 |
| 338 | 1,354 | 0 |
| 366 | 1,354 | 0 |
+--------+--------+--------+
Or like this one, that's not ideal but I will tolerate it in this case
+--------+-------------+-------+
| CIA#ST | productType | price |
+--------+-------------+-------+
| 96 | 3 | 1,359 |
| 316 | 6 | 1,354 |
| 320 | 6 | 1,354 |
| 321 | 6 | 1,354 |
| 338 | 6 | 1,354 |
| 366 | 6 | 1,354 |
+--------+-------------+-------+
For those who don't know AS400, FETCH FIRST 1 ROWS ONLY is equal to TOP 1 AND LIMIT 1
LAST does not exist in AS400 so I need to replace
SELECT LAST(Column1) AS test FROM table1
by
SELECT Column1,Column2 FROM table1 ORDER BY Column2 DESC LIMIT 1
I have tried with subselect but you can't use ORDER BY and FETCH FIRST 1 ROWS ONLY.
We are in V5R1 without any PTF.
This is an exemple of extraction
SELECT CIA#ST,CIE$OR,CIE$DI,CIEDHC
FROM PRDCM/WBDAPP03
INNER JOIN PRDCM/WBDCIE01 ON CIE#EN = DA#ENV
INNER JOIN PRDCM/WBDCIA01 ON CIA#AP = DANOID
WHERE DASTAT IN (1,4)
ORDER BY CIEDHC,DA#ENV
FETCH FIRST 5 ROWS ONLY
+--------+--------+--------+----------------------------+
| CIA#ST | CIE$OR | CIE$DI | CIEDHC |
+--------+--------+--------+----------------------------+
| 88 | 1,014 | 1,039 | 2010-08-25-09.00.00.000000 |
| 89 | 1,014 | 1,039 | 2010-08-25-09.00.00.000000 |
| 90 | 1,014 | 1,039 | 2010-08-25-09.00.00.000000 |
| 91 | 1,014 | 1,039 | 2010-08-25-09.00.00.000000 |
| 119 | 1,084 | 0 | 2010-08-25-09.00.00.000000 |
| 522 | 1,014 | 1,039 | 2010-08-25-09.00.00.000000 |
+--------+--------+--------+----------------------------+
I'll try all your suggestions.

Answer 1

Frankly, I'm a little twitchy about your schema here - there's some denormalization I'm not happy with, among other things (a multi-value column, really?). But you probably have a limited ability to change it, so... If possible, you should consider upgrading to at least V6R1 (which is what we're on), as the database gets more goodies. Thankfully, you still have CTEs, which will help a bit.
I'm assuming that what you want is the latest price change for a store (given by CIEDHC) with a call for that store in DASTAT as 1 or 4, not given by the call-time (so, what happens if an earlier group-call is 'confirmed' after a later one?). In other words, this isn't the last 'confirmed' change, it's the last 'entered' change.
I'm also assuming you have a 'store' table, with all the actual store ids defined. However, since you didn't list it, I created a CTE to manufacture one. You can (and probably should) swap it out in the resulting statement.
WITH Store (storeId) as (
SELECT DISTINCT cia#st
FROM Wbdcia00),
Price_Change (callGroup, occurredAt, productType, newPrice) as (
SELECT cie#en, ciedhc, 1, cie$or
FROM Wbdcie00
WHERE cie$or > 0
UNION ALL
SELECT cie#en, ciedhc, 4, cie$di
FROM Wbdcie00
WHERE cie$di > 0),
Confirmed_Changes (storeId, occurredAt, productType, newPrice) as (
SELECT WarehouseCall.cia#st, Change.occurredAt,
Change.productType, Change.newPrice
FROM Wbdcia00 as WarehouseCall
JOIN Wbdapp00 as Call
ON Call.danoid = WarehouseCall.cia#ap
AND Call.dastat IN (1, 4)
JOIN Price_Change as Change
ON Change.callGroup = da#env),
Latest_Change (storeId, productType, newPrice) as (
SELECT Actual.storeId, Actual.productType, Actual.newPrice
FROM Confirmed_Changes as Actual
EXCEPTION JOIN Confirmed_Changes as Remove
ON Remove.storeId = Actual.storeId
AND Remove.productType = Actual.productType
AND Remove.occurredAt > Actual.occurredAt)
SELECT store.storeId, COALESCE(Regular.newPrice, 0) as regularPrice,
COALESCE(Diesel.newPrice, 0) as dieselPrice
FROM Store
LEFT JOIN Latest_Change as Regular
ON Regular.storeId = Store.storeId
AND Regular.productType = 1
LEFT JOIN Latest_Change as Diesel
ON Diesel.storeId = Store.storeId
AND Diesel.productType = 4
Some things to note -
I figured you weren't actually giving a product a price of 0. This means that you're not looking for the individual call that went out, with both prices listed - you're going for the last change that happened, for each product. Which is why I pivoted/unpivoted that table like I did.
Needless to say, this statement reports the last entered change that was 'confirmed'. This is not the last confirmation of a change (indicated by dadthr), however.