选择与查询中的匹配列匹配的记录

This is difficult to describe, but basically here is what I want to build in MySQL, but can't figure out how to ask the proper query in Google.

I have a FOLLOWUP_CONTACT table.

Now, I want to find all of the FOLLOWUP_CONTACT records that match the column named "followupID." However, I only know the value of the column named "contactID" at the time of my query.

So, for example, if I queried FOLLOWUP_CONTACT for contactID of 123 and got back a record with followupID of 456, I want to get the FOLLOWUP_CONTACT records that match followupID of 456.

Of course, I could do two queries: one to find the followupID and the other to get the records, but this would be inefficient.

Can someone help in this case?