With语法实现SQL树结构数据查询(转)

With语法实现SQL树结构数据查询(转)BOM递归, 如果表中存放的数据是树形结构，当知道某一个节点的值时，同时想取得它所有子节点的数据，示例如下：

create table #EnterPrise
(
  Department nvarchar(50),--部门名称
  ParentDept nvarchar(50),--上级部门
  DepartManage nvarchar(30)--部门经理
)

insert into #EnterPrise select '技术部','总经办','Tom'
insert into #EnterPrise select '商务部','总经办','Jeffry'
insert into #EnterPrise select '商务一部','商务部','ViVi'
insert into #EnterPrise select '商务二部','商务部','Peter'
insert into #EnterPrise select '程序组','技术部','GiGi'
insert into #EnterPrise select '设计组','技术部','yoyo'
insert into #EnterPrise select '专项组','程序组','Yue'
insert into #EnterPrise select '总经办','','Boss'

--查询部门经理是Tom的下面的部门名称
with hgo as
(
   select *,0 as rank from #EnterPrise where DepartManage='Tom'
   union all
   select h.*,h1.rank+1 from #EnterPrise h join hgo h1 on h.ParentDept=h1.Department
)
select * from hgo

/*
Department           ParentDept                DepartManage      rank
--------------- -------------------- ----------------------- -----------
技术部               总经办                    Tom               0
程序组               技术部                    GiGi              1
设计组               技术部                    yoyo              1
专项组               程序组                    Yue               2
*/
--查询部门经理是GiGi的上级部门名称

with hgo as
(
   select *,0 as rank from #EnterPrise where DepartManage='GiGi'
   union all
   select h.*,h1.rank+1 from #EnterPrise h join hgo h1 on h.Department=h1.ParentDept
)
select * from hgo

/*
Department               ParentDept          DepartManage    rank
-------------------- ----------------------  -----------  -----------
程序组                   技术部                 GiGi           0
技术部                   总经办                 Tom            1
总经办                                          Boss           2
*/



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http://blog.csdn.net/ws_hgo/archive/2010/01/31/5274571.aspx
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