Getting users who have a field in an array

[Robust]

Worded a bit poorly, but here's what I'm essentially doing:

I have a table with users that need to update certain cached info. So I foreach each record in this row and they will affect different users, so I need to fetch the user. I can fetch a user for each record (less efficient), or I can fetch them all using getUsers at once. How can I:

1. fetch users who have a field (say, uniqueid) in my table's uniqueid column
2. pass that specific user on from the array into my update function

 

[Robust]

Just going to individually fetch users for now, it's a cron job anyway so it should be easier.