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SQL Statement How to get the "non-data" ?

Posted on 2016-09-27
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Last Modified: 2016-10-30
I have 3 tables.
Table1 : Items - Itemcode - Description - Brand -
Table 2 : Customers : Customercode - CustomerName - Salesrep
Table 3 :Transactions : Date - Reference-CustomerCode-Salesrep-Itemcode - Qty-Value-

my question is as follows:

I need to know what customers did NOT buy from that item- (i.e. there is no record in Transactions that has this customer and this item)

The second question will be how can them all ...
i.e. each customer what are the items that they did not buy (no transaction)

Thank you
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Question by:Pierre Ammoun
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Expert Comment

by:Vitor Montalvão
Comment Utility
Is this an homework or exam related question?
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Author Comment

by:Pierre Ammoun
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Nor this nor that.

I am a software developer and I have this problem that I am not being able to solve.

A brute-force solution was to do a dual -scan (scan the items and for each item scan the transactions table) but I hit a rock when the records were too much and it would take a huge amount of time that most of the time I have to "kill" the task.

Thanks
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Expert Comment

by:Pawan Kumar Khowal
Comment Utility
Try..

For question 1..

SELECT * FROM Customers c
FULL OUTER JOIN Transactions t ON c.CustomerCode = t.CustomerCode
WHERE t.customer IS NULL

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For question 2

SELECT I.Itemcode , I.Description,c.customerId FROM Customers c
OUTER APPLY
(
	SELECT I.Itemcode , I.Description , t.Transactions FROM Transactions t
	INNER JOIN Items I on t.Itemcode = I.Itemcode
	WHERE c.CustomerCode = t.CustomerCode
)p
WHERE t.customer IS NULL

Open in new window

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Author Comment

by:Pierre Ammoun
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Pawan Kumar Khowal
thank You for your feedback.

Yet in the first select statement, I fail to see the itemcode ...
The thing is that the form I am trying to design, will ask for an itemcode , and when you hit "Continue" it should show you the customers that did not take from that item.
In the first statement, I did not see any reference to an item !
Thanks
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Expert Comment

by:Vitor Montalvão
Comment Utility
These are the kind of questions I had when learning databases. That's why I asked.

You have some options but I like the NOT EXISTS:
-- Question 1
SELECT Customercode, CustomerName, Salesrep
FROM Customers
WHERE NOT EXISTS (SELECT 1 
        FROM Transactions 
        WHERE Transactions.CustomerCode =  Customers.Customercode
             AND Itemcode = @ItemCodeToSearch)

-- Question 2
SELECT Customers.Customercode, Customers.CustomerName, Items.Itemcode, Items.Description 
FROM Customers
    INNER JOIN Transactions ON Transactions.CustomerCode =  Customers.Customercode
    INNER JOIN Items ON Items.Itemcode = Transactions.Itemcode 
WHERE NOT EXISTS (SELECT 1 
        FROM Transactions T2
        WHERE T2.CustomerCode =  Customers.Customercode
             AND T2.Itemcode = Items.Itemcode)

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NOTE: I didn't test the code so please check if returns what you need.
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Expert Comment

by:Pawan Kumar Khowal
Comment Utility
try this ..

DECLARE @ItemCode AS VARCHAR(10) = 'abc'

SELECT I.Itemcode , I.Description, c.customerId FROM Customers c
OUTER APPLY
(
	SELECT I.Itemcode , I.Description , t.Transactions FROM Transactions t
	INNER JOIN Items I on t.Itemcode = I.Itemcode
	WHERE c.CustomerCode = t.CustomerCode
	AND t.Itemcode = @ItemCode
)p
WHERE t.customer IS NULL

Open in new window

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Expert Comment

by:Pawan Kumar Khowal
Comment Utility
Is the second query I posted earlier is fine for you ?
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Author Comment

by:Pierre Ammoun
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Pawan Kumar Khowal

Still checking it.... :)
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Author Comment

by:Pierre Ammoun
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Vitor Montalvão

Thank you  . The first part is covered by your answer.

Yet the second one, gives me an error (error correlating fields)

Thanks
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Expert Comment

by:Vitor Montalvão
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Please post the error since I can't test it.
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Author Comment

by:Pierre Ammoun
Comment Utility
Screenshot--5-.png
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LVL 45

Expert Comment

by:Vitor Montalvão
Comment Utility
You missed the alias in the subselect:
WHERE NOT EXISTS (SELECT 1
        FROM Transactions T2
        WHERE T2.CustomerCode =  Customers.Customercode
             AND T2.Itemcode = Items.Itemcode)
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Author Comment

by:Pierre Ammoun
Comment Utility
Dear Vitor,
same error !Screenshot--8-.png
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Expert Comment

by:Pawan Kumar Khowal
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@Author - Can you try mine if possible ?
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Author Comment

by:Pierre Ammoun
Comment Utility
Pawan Kumar Khowal

Thank you once again but my problem with your second answer is that in VFP (my programming language) I do not have the Apply Command in SQL Statement !
I think I made a mistake by saying that I was looking for a SQL Statment... I thought that VFP works the same way as SQL . Seems that there are certain commands not applicable !

Thanks again!
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Expert Comment

by:Pawan Kumar Khowal
Comment Utility
Okies,

SELECT I.Itemcode , I.Description,c.customerId FROM Customers c
FULL OUTER JOIN 
(
	SELECT I.Itemcode , I.Description , t.Transactions FROM Transactions t
	INNER JOIN Items I on t.Itemcode = I.Itemcode	
)p
ON c.CustomerCode = p.CustomerCode
WHERE p.customer IS NULL

Open in new window

0
 
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Expert Comment

by:Vitor Montalvão
Comment Utility
You're using VFP and this may have impact on the query. It should work perfectly in SQL Server.
Lets try to make a small modification:
SELECT Accounts.Account, Accounts.AccName, Items.Itemcode, Items.Description 
FROM Accounts
    INNER JOIN Transtok 
        INNER JOIN Items ON Items.Itemcode = Transtok.Itemcode 
    ON Transtok.Customer =  Accounts.Account
WHERE NOT EXISTS (SELECT 1 
        FROM Transtok T2
        WHERE T2.Customer =  Accounts.Account
             AND T2.Itemcode = Items.Itemcode)

Open in new window

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Author Comment

by:Pierre Ammoun
Comment Utility
Vitor Montalvão

Same Error ! error correlating fields..
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LVL 17

Expert Comment

by:Pawan Kumar Khowal
Comment Utility
Check for a tool that will convert this tsql to VFP.. May be tool available online.
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Expert Comment

by:Vitor Montalvão
Comment Utility
I guess VFP doesn't accept very well the JOIN so here's an old school solution:
SELECT Accounts.Account, Accounts.AccName, Items.Itemcode, Items.Description 
FROM Accounts, Transtok,Items 
WHERE Items.Itemcode = Transtok.Itemcode 
    AND Transtok.Customer =  Accounts.Account
    AND NOT EXISTS (SELECT 1 
        FROM Transtok T2
        WHERE T2.Customer =  Accounts.Account AND T2.Itemcode = Items.Itemcode)

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Author Comment

by:Pierre Ammoun
Comment Utility
Vitor Montalvão

Sorry,
but same problem again !
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Expert Comment

by:PortletPaul
Comment Utility
Only have a phone but this might help q1

Select c.*
From customers c
Left join transactions t on c.custno = t.custno
Where t.itemno IS NULL
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Accepted Solution

by:
Vitor Montalvão earned 500 total points
Comment Utility
What version of VFP are you using? Looks like VFP is very weak for SQL commands.
One last try, please:
SELECT Accounts.Account, Accounts.AccName, Items.Itemcode, Items.Description 
FROM Accounts
    INNER JOIN Transtok ON Transtok.Customer =  Accounts.Account
    INNER JOIN Items ON Items.Itemcode = Transtok.Itemcode 
    LEFT JOIN Transtok T2 ON T2.Customer =  Accounts.Account AND T2.Itemcode = Items.Itemcode
WHERE T2.Itemcode IS NULL

Open in new window

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Author Comment

by:Pierre Ammoun
Comment Utility
I m using vfp 9
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Expert Comment

by:Vitor Montalvão
Comment Utility
I m using vfp 9
I guess is the last version, right?

Did you try my last query?
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Author Comment

by:Pierre Ammoun
Comment Utility
Vitor Montalvão


We are getting somewhere ! Now no more error, but this time the Query returns an empty cursor.
Which is not possible. I know for a fact that there are many items not linked to any transactions (per customer)

Thanks
0
 
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Expert Comment

by:Vitor Montalvão
Comment Utility
Ok I need some data mockup.
Can you post non real data sample so I can play with it to verify what's missing?
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Author Comment

by:Pierre Ammoun
Comment Utility
OK.  I would need few min.
Thanks
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Author Comment

by:Pierre Ammoun
Comment Utility
Which format ?
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Expert Comment

by:Vitor Montalvão
Comment Utility
Excel or CSV will be good so I can import it easily.
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Author Comment

by:Pierre Ammoun
Comment Utility
Vitor Montalvão,

Thank you very much for your efforts.

I took the first SQL Statement and tweaked it a little (put it in a SCAN function) and got what I needed.

Thank you very very much.

Regards
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Expert Comment

by:PortletPaul
Comment Utility
Why is a suggested query using outer apply that could not be used chosen as an assisted answer?

Points should not be allocated for mere participation or volune of participation. The enduring value of the question/answer database is reduced if that happens.
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Author Comment

by:Pierre Ammoun
Comment Utility
PortletPaul

The outer Apply syntax did not work with me and therefore I did not consider it as part of the solution.
As I said it is my mistake that I did not specify that it was for a VFP application and not a "pure" SQL hence the impossibility for me to test the outer apply syntax.

I hope I could clear the matter and once again I apologize for not being accurate in the question.
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Expert Comment

by:Vitor Montalvão
Comment Utility
Pierre, can you close this question properly?
Cheers.
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Expert Comment

by:Vitor Montalvão
Comment Utility
I don't remember anymore which comments were marked as solution and looks like Pierre didn't return to close this properly.
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Expert Comment

by:PortletPaul
Comment Utility
previously
ID: 41817753 350 points
ID: 41817754 150 points

but that was incorrect
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