Question

I have 3 tables

1. Links
   Link ID
   Link Name
   GroupID (FK into Groups)
   SubGroupID (FK into Subgroups)

2. Groups
   GroupID
   GroupName

3. SubGroup
   SubGroupID
   SubGroupName
   GroupID (FK into Groups)

Every link needs to have a GroupID but teh SubGroupID is optional. How do i write a SQL query to show:

Links.LinkName, Groups.GroupName, SubGroup.SubGroupName

For the records with no subgroup just put a blank entry in that field. If i have 250 link rows, i should get back 250 reecords from this query.

Is there a way to do this in one query or do i need to do multiple queries?

Answer 1

This assumes that there is at most only 1 subgroup per group. if there are more, then you have the potential to get additional records.

select links.linkname, groups.groupname, subgroup.subgroupname from links   inner join groups on (links.groupid = groups.groupid)   left outer join subgroup on (links.subgroupid = subgroup.subgroupid)