| stats latest(Model) as Model BY PhoneNumber
| rename COMMENT as "Above produces one record per PhoneNumber on file. use latest() for most recent. "
| rename COMMENT as "Add all the records then stats them together"
| inputlookup append=t phonebook.csv
| stats values(Model) as Model values(UserName) as UserName by PhoneNumber
| rename COMMENT as "Fill in the word unknown for any that had no records on the inventory index"
| eval Model=coalesce(Model,"unknown")
Remember that last() refers to the last record returned, which is usually the earliest record on the index.