What is the problem with the logic in my UPDATE statement?

Question

Hello,

I would appreciate some help with an UPDATE statement.

I want to update tblOrderHead with the content from tblCustomer where the intDocumentNo corresponds to the parameter @intDocumentNo. But when I run the my statement, the order table is only updated with the content from the first row of the customer table.

What is the problem with my logic?

I use Microsoft SQL Server.

Thanks,

Stefan

UPDATE      dbo.tblOrderHead
SET         dbo.tblOrderHead.intCustomerNo   = @intCustomerNo ,
            dbo.tblOrderHead.intPaymentCode  = dbo.tblCustomer.intPaymentCode,
            dbo.tblOrderHead.txtDeliveryCode = dbo.tblCustomer.txtDeliveryCode,
            dbo.tblOrderHead.txtRegionCode   = dbo.tblCustomer.txtRegionCode,
            dbo.tblOrderHead.txtCurrencyCode = dbo.tblCustomer.txtCurrencyCode,
            dbo.tblOrderHead.txtLanguageCode = dbo.tblCustomer.txtLanguageCode
FROM        dbo.tblOrderHead
INNER JOIN  dbo.tblCustomer ON dbo.tblOrderHead.intOrderNo = @intDocumentNo

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Solution

If anyone as stupid as me out there thing the same thing, this is how you solve it:

UPDATE      dbo.tblOrderHead
SET         dbo.tblOrderHead.intCustomerNo   = @intCustomerNo ,
            dbo.tblOrderHead.intPaymentCode  = dbo.tblCustomer.intPaymentCode,
            dbo.tblOrderHead.txtDeliveryCode = dbo.tblCustomer.txtDeliveryCode,
            dbo.tblOrderHead.txtRegionCode   = dbo.tblCustomer.txtRegionCode,
            dbo.tblOrderHead.txtCurrencyCode = dbo.tblCustomer.txtCurrencyCode,
            dbo.tblOrderHead.txtLanguageCode = dbo.tblCustomer.txtLanguageCode
FROM        dbo.tblOrderHead
INNER JOIN  dbo.tblCustomer ON dbo.tblOrderHead.intCustomerNo = dbo.tblCustomer.intCustomerNo
AND         dbo.tblOrderHead.intOrderNo = @intDocumentNo

Answer 1

Problem is that, you are not specifying the condition on which the 2 tables tblOrderHead, tblCustomer need to be joined!

you need something like

INNER JOIN  dbo.tblCustomer 
ON dbo.tblOrderHead.someColumn = dbo.tblCustomer.someColumn
and dbo.tblOrderHead.intOrderNo = @intDocumentNo