SQL Server遞歸父/子相同表使用相同字段

Question

我需要讓父母和所有孩子從同一張桌子...

運行此查詢時：

select location, children  from lochierarchy where parent ='HSAGCF'

結果：

Location    Children
--------    ------------
HSAGCFSMF   1
HSAGEE      1
HSAGGAI     0
HSAGPO      1
HSAGSA      1
HSAGSACC    1
HSAGSAFR    0
HSAGSARV    0
HSAGSASG    0
HSAGSC      1
HSAGSD      1
HSAGSI      1
HSAGSO      1
HSAGSR      0
HSAGST      0
HSAGSTTO    0

當位置有子代= 1時，子代中有更多子代

如何執行遞歸操作，以使此查詢的每個位置都高於其子代= 1的位置，然后再次運行查詢，如下所示：

select location 
  from lochierarchy 
 where parent in ( 'HSAGCFSMF', 'HSAGEE', 'HSAGGAI', 'HSAGPO', 'HSAGSA',
                   'HSAGSACC','HSAGSAFR', 'HSAGSARV', 'HSAGSASG', 'HSAGSC',
                   'HSAGSD', 'HSAGSI', 'HSAGSO', 'HSAGSR', 'HSAGST', 
                   'HSAGSTTO', 'HSAGSV', 'HSAGU1', 'HSAGU2', 'HSAGU3', 'HSAGU4')


locations     Children
----------    ------------
HSAGCFSMF       1
HSAGEE          1
HSAGGAI         0
HSAGPO          1
HSAGSA          1
HSAGSACC        1
HSAGSAFR        0
HSAGSARV        0
HSAGSASG        0
HSAGSC          1
HSAGSD          1
HSAGSI          1
HSAGSO          1
HSAGSR          0
HSAGST          0
HSAGSTTO        0
HSAGSV          0

需要重復執行此遞歸操作，直到所有位置的子代均為= 0

Answer 1

如果您使用的是SQL 2005或更高版本，則可以使用遞歸公用表表達式。 像這樣：

declare @parent varchar(20) = 'HSAGCF';

with cte as (
   select location, parent 
   from lochierarchy
   where location = @parent

   union all

   select c.location, c.parent
   from lochierarchy as c
   join cte as p
      on c.parent = p.location
)
select *
from cte;

如果您想要通往樹中葉節點的路徑，我將其作為練習留給讀者。