Question

I have two tables as follows

Group
Id,   Name,        ParentId
1,    North,       NULL
2,    South,       NULL
3,    London,      2
4,    Brighton,    2
5,    Fulham,      3
6,    SuperStores, NULL

StoreAndGroup
Id,   StoreId,     GroupId
1,    41,          2
2,    52,          3
3,    88,          5
4,    88,          6
5,    41,          6

etc

I want to produce a table that shows all stores that belong to each group (including subgroups), so the above would become

GroupId, StoreId
2,       41
2,       52
2,       88
3,       52
3,       88
5,       88
6,       88
6,       41

I can use a recursive cte to show me all children of a particular group but am a bit stuck as to how to incorporate the additional data.

Answer 1

Actually it turned out to be a simple join

WITH
   cteGroups (Id, GroupName, ParentGroupId, GroupLevel)
   AS
   (
     SELECT Id, GroupName, ParentGroupId
     FROM Dim_Group
     UNION ALL
     SELECT g.Id, g.GroupName, g.ParentGroupId
     FROM Dim_Group g
      INNER JOIN cteGroups cg
        ON g.ParentGroupId = cg.Id
  )

  select * from cteGroups inner join dim_groupmember on cteGroups.Id = dim_groupmember.groupid

Darren