UPDATE Syntax with ORDER BY, LIMIT and Multiple Tables

Question

Learning SQL, sorry if this is rudimentary. Trying to figure out a working UPDATE solution for the following pseudoish-code:

UPDATE tableA 
SET          


        

Answer 1

You can use following query syntax:

update work_to_do as target
   inner join (
      select w. client, work_unit
      from work_to_do as w
         inner join eligible_client as e on e.client = w.client
      where processor = 0
      order by priority desc
      limit 10
   ) as source on source.client = target.client
      and source.work_unit = target.work_unit
   set processor = @process_id;

This works perfectly.