階層の最上位の親を取得する SQL Server 関数

top から childs への再帰 cte の場合:

with cte as(
  select *, code as ultimate from t where code = under
  union all
  select t.*, c.ultimate from t
  join cte c on c.code = t.under
  where t.code <> t.under
)
select * from cte

データの場合:

create table t (code int, name varchar(100), under int)
insert into t values
(1, 'National Sales Manager', 1),
(2, 'regional sales manager', 1),
(3, 'area sales manager', 2),
(4, 'sales manager', 3),
(5, 'a', 5),
(6, 'b', 5),
(7, 'c', 5),
(8, 'd', 7),
(9, 'e', 7),
(10, 'f', 9),
(11, 'g', 9)

出力を生成します:

code    name                    under   ultimate
1       National Sales Manager  1       1
5       a                       5       5
6       b                       5       5
7       c                       5       5
8       d                       7       5
9       e                       7       5
10      f                       9       5
11      g                       9       5
2       regional sales manager  1       1
3       area sales manager      2       1
4       sales manager           3       1

フィドル http://sqlfiddle.com/#!6/17c12e/1