Как да получа съответния текст, разделен със запетая, за низ от кодове, разделени със запетая?

Може да има по-прости решения за това, но ето един начин.

Структура на таблицата

create table Locations(LocationID int, Location varchar(50))
create table OtherTable(ID int, Locations varchar(max))

Тестови данни

insert into Locations values(1, 'Location <1>')
insert into Locations values(2, 'Location <2>')
insert into Locations values(3, 'Location <3>')
insert into Locations values(4, 'Location <4>')
insert into Locations values(5, 'Location <5>')

insert into OtherTable values (1, '')
insert into OtherTable values (2, '2')
insert into OtherTable values (3, '1, 3 ,5')

Заявка

;with cte as
(
  select 
    T.ID,
    coalesce(L.Location, '') as Location
  from OtherTable as T
    cross apply
      (select cast('<r>'+replace(T.Locations, ',', '</r><r>')+'</r>' as xml)) LocXML(XMLCol)
    cross apply
      LocXML.XMLCol.nodes('r') LocID(IDCol) 
    left outer join Locations as L
      on L.LocationID = LocID.IDCol.value('.', 'int')
)
select
  C1.ID,
  stuff((select ', '+C2.Location
         from cte as C2 
         where C1.ID = C2.ID
         for xml path(''), type).value('text()[1]', 'nvarchar(max)'), 1, 2, '') as Locations
from cte as C1
group by C1.ID

Резултат

ID  Locations
--- ----------------------------------------
1   
2   Location <2>
3   Location <1>, Location <3>, Location <5>