You should be able to link to the DNN table, PortalAlias with the PortalID and display the field HTTPAlias
here is a select statement
SELECT dbo.Portals.PortalID, dbo.PortalAlias.HTTPAlias
FROM dbo.Portals INNER JOIN
dbo.PortalAlias ON dbo.Portals.PortalID = dbo.PortalAlias.PortalID