Dynamic pivot

I am trying to use pivot in dynamic fashion .

I have data in

and I want to get result in this format

I have achieved this result by

select * from ( (select users, products, sale from sales))

pivot(   

sum(sale)   for products IN ('product 1', 'product 2', 'product 3', 'product 4', 'product 5')

)

The product range may increase rapidly in future, so I want dynamic pivoting in 'IN' clause.