I think that this is really easy, I just have never done it before.
Basically I have a two columned table: table1
It has the columns id, and name
talble1: (all have names)
Then I have
table2: (Some names are null)
I basically want to go through table2 and for any null names use the id to look up the name in table1 and then update table2 with this name.