Query to update data with related data

[thesolution]

I have a junction table, let's call it table Junction. It has several fields, only one of which is important for my question, personnelID. This field is linked to another table, table Personnel. I need to replace all the records in table Junction's personnelID field with another field, username. Only problem is that there are thousands of records, so obviously I can't do it by hand.

Is it possible to run some type of query to replace all records by comparing certain fields? Thanks.

 

[jdraw]

Please describe your junction table in more detail.
What other tables are you using?
Why do you want to put username in the junction table? Usually the junction table wikk have the PK (primary key) of the person in the personnel table (often personnelId), and the PK of the other table that has a many to many relationship with Personnel.