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

Pierre Ammoun
Pierre Ammoun used Ask the Experts™
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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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Vitor MontalvãoIT Engineer
Distinguished Expert 2017

Commented:
Is this an homework or exam related question?
Pierre AmmounIT Consultant

Author

Commented:
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
Pawan KumarDatabase Expert
Awarded 2016
Top Expert 2016

Commented:
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

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Pierre AmmounIT Consultant

Author

Commented:
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
Vitor MontalvãoIT Engineer
Distinguished Expert 2017

Commented:
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.
Pawan KumarDatabase Expert
Awarded 2016
Top Expert 2016

Commented:
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

Pawan KumarDatabase Expert
Awarded 2016
Top Expert 2016

Commented:
Is the second query I posted earlier is fine for you ?
Pierre AmmounIT Consultant

Author

Commented:
Pawan Kumar Khowal

Still checking it.... :)
Pierre AmmounIT Consultant

Author

Commented:
Vitor Montalvão

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

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

Thanks
Vitor MontalvãoIT Engineer
Distinguished Expert 2017

Commented:
Please post the error since I can't test it.
Pierre AmmounIT Consultant

Author

Commented:
Screenshot--5-.png
Vitor MontalvãoIT Engineer
Distinguished Expert 2017

Commented:
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)
Pierre AmmounIT Consultant

Author

Commented:
Dear Vitor,
same error !Screenshot--8-.png
Pawan KumarDatabase Expert
Awarded 2016
Top Expert 2016

Commented:
@Author - Can you try mine if possible ?
Pierre AmmounIT Consultant

Author

Commented:
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!
Pawan KumarDatabase Expert
Awarded 2016
Top Expert 2016

Commented:
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

Vitor MontalvãoIT Engineer
Distinguished Expert 2017

Commented:
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

Pierre AmmounIT Consultant

Author

Commented:
Vitor Montalvão

Same Error ! error correlating fields..
Pawan KumarDatabase Expert
Awarded 2016
Top Expert 2016

Commented:
Check for a tool that will convert this tsql to VFP.. May be tool available online.
Vitor MontalvãoIT Engineer
Distinguished Expert 2017

Commented:
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)

Open in new window

Pierre AmmounIT Consultant

Author

Commented:
Vitor Montalvão

Sorry,
but same problem again !
PortletPaulEE Topic Advisor
Most Valuable Expert 2014
Awarded 2013

Commented:
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
IT Engineer
Distinguished Expert 2017
Commented:
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

Pierre AmmounIT Consultant

Author

Commented:
I m using vfp 9
Vitor MontalvãoIT Engineer
Distinguished Expert 2017

Commented:
I m using vfp 9
I guess is the last version, right?

Did you try my last query?
Pierre AmmounIT Consultant

Author

Commented:
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
Vitor MontalvãoIT Engineer
Distinguished Expert 2017

Commented:
Ok I need some data mockup.
Can you post non real data sample so I can play with it to verify what's missing?
Pierre AmmounIT Consultant

Author

Commented:
OK.  I would need few min.
Thanks
Pierre AmmounIT Consultant

Author

Commented:
Which format ?
Vitor MontalvãoIT Engineer
Distinguished Expert 2017

Commented:
Excel or CSV will be good so I can import it easily.
Pierre AmmounIT Consultant

Author

Commented:
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
PortletPaulEE Topic Advisor
Most Valuable Expert 2014
Awarded 2013

Commented:
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.
Pierre AmmounIT Consultant

Author

Commented:
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.
Vitor MontalvãoIT Engineer
Distinguished Expert 2017

Commented:
Pierre, can you close this question properly?
Cheers.
Vitor MontalvãoIT Engineer
Distinguished Expert 2017

Commented:
I don't remember anymore which comments were marked as solution and looks like Pierre didn't return to close this properly.
PortletPaulEE Topic Advisor
Most Valuable Expert 2014
Awarded 2013

Commented:
previously
ID: 41817753 350 points
ID: 41817754 150 points

but that was incorrect

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