I have a list of two columns consisting of part number and quantity, some of
the lines contain duplicate part numbers.

Example

Part Number Qty
311 10
311 5
312 20
313 5
313 5

Is there any way I can merge the duplicate part numbers into one line whilst
combining the quantites to read as follows?

Part Number Qty
311 15
312 20
313 10

Have a very large database to work through and this would make my life a lot
easier :0)