SQL过滤表中的数据

Question

I have table with sales documents and invoices eg

SalesDoc | Invoice | InvoiceType
------------------------------------
Doc1     | Inv1    | A
Doc1     | Inv2    | B
Doc1     | Inv3    | C
Doc2     | Inv1    | A
Doc2     | Inv2    | C
Doc3     | Inv1    | A
Doc3     | Inv2    | B

Each Sales document can have more than one invoice eg standard invoice or proforma..

I need to filter that table to receive below table

So If for Sales doc exist incoice C then show only this row for that sales doc, if not then check for type B and then for type A.

SalesDoc | Invoice | InvoiceType
-----------------------------------
Doc1     | Inv3    | C
Doc2     | Inv2    | C
Doc3     | Inv2    | B

I know that I can store sales docs in temp table and then loop (using cursor) and filter source table to delete unnecessary records But I want to be sure if is any other solution than loop to achieve it

Thanks Tomek

Answer 1

Depending on the greater logic, you could do this with aggregates:

Select  SalesDoc, Max(Invoice) as Invoice, Max(InvoiceType) as InvoiceType
FROM MYSALESTABLE
GROUP BY SalesDoc