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# Need help writing a query

Posted on 2015-01-13
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Experts,

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ItemDetails.docx
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Question by:Tpaul_10
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Accepted Solution

Simon earned 2000 total points
ID: 40547980
To clarify:
need to get the list of distinct ItemIDs where an Item has an ItemCode stating with “G” and it’s previous ItemCode starting with “C”
You write HAS an itemCode starting wtih 'G' (implying that this is the CURRENT status), but, you expect to see ID2 in your results even though that doesn't have a current itemCode starting with G. It does have two sequential historic records with ItemCodes GP and CF (with historicIDs 3 and 2 respectively).

Can I just confirm that the chronological order of the ItemHistoryID values runs 1,2,3,4,5,n..0, where 1 is the oldest status, 2 is the next oldest status and n is the most recently superseded status?

Your item ID3 has 3 rows, all with ItemHistoryID =0. How can the same item have 3 different 'latest/current' statuses?
('IP3', 0, 'GP'),
('IP3', 0, 'N'),
('IP3', 0, 'CF'),
('IP3', 1, 'IP')

** In listings below, replace t1 with the name of your table  **

This code gets you CURRENT itemCode like G% with immediate predecessor like C%
``````with cteCurr as (
select ItemID,ItemHistoryID,ItemCode from t1 where ItemHistoryID=0),
cteHist as (
select ItemID,ItemHistoryID,ItemCode
,row_number() over (partition by itemID order by ItemHistoryID desc) as HistRank
from t1 where ItemHistoryID>0)

select cteCurr.ItemID,cteCurr.ItemCode as CurrCode,cteHist.itemCode as LastCode
from cteCurr inner join ctehist on ctecurr.itemID=ctehist.itemID
where cteCurr.itemcode like 'G%' and cteHist.Itemcode like 'C%' and cteHist.HistRank = 1
``````

This code gets you ANY itemCode  like G% with immediate predecessor like C%
``````with cteCurr as (
select ItemID,ItemHistoryID,ItemCode,0 as HistRank from t1 where ItemHistoryID=0),
cteHist as (
select ItemID,ItemHistoryID,ItemCode
,row_number() over (partition by itemID order by ItemHistoryID desc) as HistRank
from t1 where ItemHistoryID>0),
cteAll as (select * from cteCurr UNION ALL select * from cteHist)

select c.ItemID,c.ItemCode as CurrCode,p.itemCode as LastCode
from cteAll c inner join cteAll p on c.itemID=p.itemID and p.histrank=c.histrank+1
where c.itemcode like 'G%' and p.Itemcode like 'C%'
``````

This is the test table for the above listings:
``````CREATE TABLE T1
([ItemId] varchar(3), [ItemHistoryID] int, [ItemCode] varchar(2))
;

INSERT INTO T1
([ItemId], [ItemHistoryID], [ItemCode])
VALUES
('IP1', 0, 'GN'),
('IP1', 1, 'N'),
('IP1', 2, 'CF'),
('IP2', 0, 'GN'),
('IP2', 1, 'N'),
('IP2', 2, 'CF'),
('IP2', 3, 'GP'),
('IP3', 0, 'GP'),
('IP3', 0, 'N'),
('IP3', 0, 'CF'),
('IP3', 1, 'IP')
;
``````
0

Author Comment

ID: 40548039
Thanks for the quick reply Simon and appreciate your questions. Here are the details and please excuse me for the confusion.

1. Not considering the historyID, I need to find out the items having itemcode starting with "C%" with the next row/transaction starting with  "G%".  (That was the reason I have had IP2 in my output.)
2. Yes, 1 is the oldest and 0 is the latest
3. on IP3 it should 0,1,2,3 and it was a type from me.

I have tried the above code and not returning rows but I will verify it again and hope I have clarified what I am looking for in #1

Thanks again.
0

LVL 18

Expert Comment

ID: 40549318
Hi,

>"Not considering the historyID"
It seems you do need to consider (make use of) the ItemHistoryID column to order the data. If you don't order the data by ItemID then ItemHistoryID, there is no way of determining which the 'next row/transaction' will be.

Here's some revised code in a self-contained block, with the test data table included to make it easy to check the results.
``````declare @t1  table (ItemID  char(3),ItemHistoryID  int,ItemCode  varchar(5))

insert into @t1 values
('IP1',	0,	'GN'),
('IP1',	1,	'N'),
('IP1',	2,	'CF'),

('IP2',	0,	'GN'),
('IP2',	1,	'N'),
('IP2',	2,	'CF'),
('IP2',	3,	'GP'),

('IP3',	0,	'GP'),
('IP3',	1,	'N'),
('IP3',	2,	'CF'),
('IP3',	3,	'IP');

;with cteCurr as (
select ItemID,ItemHistoryID,ItemCode,0 as HistRank from @t1 where ItemHistoryID=0),
cteHist as (
select ItemID,ItemHistoryID,ItemCode
,row_number() over (partition by itemID order by ItemHistoryID desc) as HistRank
from @t1 where ItemHistoryID>0),
cteAll as (select * from cteCurr UNION ALL select * from cteHist)

select c.ItemID,c.ItemCode as CurrCode,p.itemCode as PrevCode ,c.ItemHistoryID as HistID,p.ItemHistoryID as PrevHistID
from cteAll c inner join cteAll p on c.itemID=p.itemID and p.histrank=c.histrank+1
where c.itemcode like 'G%' and p.Itemcode like 'C%'
``````

The result:
0

Author Closing Comment

ID: 40555615
Very accurate and quick help, appreciate it.
Thank You Simon, appreciate all your help with the detailed explanation
0

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