Need Help Creating Table From Excel File

I am stuck with a problem where I need to create a new table from an excel file. In detail my problem is;
The excel file contains an order from a customer, like below,
BOM Component Qty
123 abc 2
123 def 2
234 ert 1
234 qwe 1
234 uio 1

I need to create a table from this data like;
Qty Partno
1 123
4 abc
4 def
1 234
2 ert
2 qwe
2 uio

NB! In reality the components are numbers not letters.
The qty for BOM is always 1 and the component 2xqty.

It is important that the BOM number is listed first and thereafter its components.

So I need to somehow associate the BOM number with its components and list them together as a group.
I just cannot figure out how to do this.

ANy help is greatly appreciated.