SQL Server 根据树状结构表生成以/号分割的路由字符串

很多情况下，我们有必要把树形结构进行数据梳理。比如，要方便的过滤出一个父节点下的所有子节点等等。。。

这个时候，我们可以生成一个路径表字符串，在应用时只需要对该字符串进行索引即可达成目的。

目标：按图示的部门结构树，获取本身的完整路径字符串。比如，前道工序部门，其部门代码为PDTE，上级部门为PD生产部，按结构树获取到一个/PD/PDTE/的字符串。

　　先来一个简单点的展示：

WITH T AS (SELECT     CAST('/' + DeptCode + '/' AS NVARCHAR(MAX)) AS DpPath, DeptRKEY AS DpKey
                         FROM          Base_Department
                         WHERE      (ILevel = 1)--指定父级起点
                         UNION ALL
                         SELECT     CAST(t.DpPath + D.DeptCode + '/' AS NVARCHAR(MAX)) AS DpPath, D.DeptRKEY AS DpKey
                         FROM         Base_Department AS D INNER JOIN
                                               T ON D.ParentRKEY = T.DpKey)--设置递归关联
    SELECT     DpPath, DpKey     FROM         T--输出结果

　　输出如下图：

　　然后开个稍微复杂点的，带上级机构关联上：

WITH T AS (SELECT     '/' + CAST(DeptCode AS NVARCHAR(MAX)) + '/' AS DpPath, DeptRKEY AS DpKey, DeptNameLL AS DpNameLL, DeptNameLI AS DpNameLI, ILevel AS DpLevel, ISEQ AS DpSEQ, 
                                                BranchRKEY
                         FROM          Base_Department
                         WHERE      (ILevel = 1)
                         UNION ALL
                         SELECT     CAST(t.DpPath + D.DeptCode + '/' AS NVARCHAR(MAX)) AS DpPath, D.DeptRKEY AS DpKey, D.DeptNameLL AS DpNameLL, D.DeptNameLI AS DpNameLI, D.ILevel AS DpLevel, 
                                               D.ISEQ AS DpSEQ, D.BranchRKEY
                         FROM         Base_Department AS D INNER JOIN
                                               T ON D.ParentRKEY = T.DpKey)
    SELECT     '/' + BranchCode + '/' AS DpPath, BranchCode AS DpKey, BranchNameLL AS DpNameLL, BranchNameLI AS DpNameLI, 0 AS DpLevel, 0 AS DpSEQ
     FROM         Base_Branch
UNION ALL
SELECT     '/' + B.BranchCode + T.DpPath AS Expr1, STR(T.DpKey) AS DpKey, T.DpNameLL, T.DpNameLI, T.DpLevel, T.DpSEQ
FROM         T INNER JOIN
                      Base_Branch AS B ON T.BranchRKEY = B.BranchRKEY

　　输出如下：

　　如果，某些场合下，就能很好的利用这个DpPath了。