Special case for data flow control

souces table:
InvNo QTY SALES DISC
1001 3 300 20

Target table:
InvNo Type Measures
1001 QTY 3
1001 SALES 300
1001 DISC 20

I think we can use the sql statement with union of 3 sql statement like this format:

select InvNo, 'QTY'AS TYPE,QTY from sourcestable
union
select InvNo,'SALES' AS TYPE, SALES from sourcestable
Union
select InvNo,'DISC' AS TYPE, DISC from sourcestable

But I think thgis is not the better solution since sql with union will be slower.
May I know any tool in the data flow able to cater this situation?How to use the related tool?
Thanks in advance.

I just have a solution for this case.
Unpivot tool at the data flow component will be very helpful for this case.
Thanks