SQL Query Help

[WallyByGolly]

Table Strucure: 2 columns...1 labeled Part Number and the other Serial Number.

Part Number column has duplicate part numbers and non duplicate serial numbers... example:
PN SN
123456 1
123456 2
654321 1

I have fallen and bumped my head.
What is SQL query that will return all Serial Numbers for a Given Part number....to late in the day to think

 

[Mercury2]

Select * From MyTable Where PN = 123456

This qry will return all rows of MyTable where PN = 123456, i.e.

PN SN
123456 1
123456 2