I need a formula to find how many productA(f.ex. apples) have I sold at the
same time as i have sold productB (f.ex bananas) (with identical
invoicenumber), f.ex.:
invoiceno. product kg
50 apples 1,00
50 bananas 2,00
51 apples 1,00
52 apples 1,00
53 apples 1,00
53 bananas 2,00
54 bananas 2,00
55 apples 1,00
55 bananas 2,00