I would like you to help me with a problem, because I am learning and I have an urgent job: I have a table called 'vendor', another called 'invoice', they are related to a foreign key. In addition there is another table called 'product', related to 'invoice'.
I need to show the products that each vendor has sold, worth the redundancy.
With GROUP BY I try to group by seller, but, I do not know how to make all the products that have sold out. Example image:
The problem is a typical case of a table pivot. Where you need to pass a result like this:
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| Vendedor | Producto | Total |
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| Juan | Carne | 100 |
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| Pedro | Leche | 20 |
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| Pedro | Carne | 60 |
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to one this way:
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| Vendedor | Carne | Leche | Total |
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| Juan | 100 | 0 | 100 |
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| Pedro | 60 | 20 | 80 |
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It is a common question, in some database engines it is easier to solve it than in others, sometimes it is even easier to solve the issue using a programming language I suggest to review: link , or google more about how to make pivot queries.