数据库环境：SQL SERVER 2005
有一层次表的数据如下图1，要实现图2的效果，即将层次结构的路径按行显示，
第一列显示的是叶子节点，后面则是分枝节点，最后是根节点。
要解决的问题：
1.递归实现树形查询
2.从根节点到叶子节点编成一组
3.动态行转列
好了，我们依次来解决这些问题。
0.建表，导入基础数据
WITH x0 AS(SELECT 1 AS id,'1xx' AS name,2 AS fatherID UNION ALLSELECT 2 AS id,'2xx' AS name,3 AS fatherID UNION ALLSELECT 3 AS id,'3xx' AS name,0 AS fatherID UNION ALLSELECT 4 AS id,'4xx' AS name,3 AS fatherID UNION ALLSELECT 0 AS id,'0xx' AS name,NULL AS fatherID)SELECT * INTO #t FROM x0
1.递归分组
分组的组号依据叶子节点的id而定，从叶子节点追溯到根节点，它们属于同一组。
/*递归实现层次查询*/WITH x0 ( id, name, fatherID, way, level ) AS ( SELECT id , name , fatherID , CONVERT(VARCHAR(50), CAST(id AS VARCHAR(2))) AS way , id AS level FROM #t t1 /*从叶子节点开始递归*/ WHERE NOT EXISTS ( SELECT NULL FROM #t t2 WHERE t2.fatherID = t1.id ) UNION ALL SELECT t1.id , t1.name , t1.fatherID , CONVERT(VARCHAR(50), CAST(t1.id AS VARCHAR(2)) + '->' + t2.way) AS way ,--路径 t2.level--组别 FROM #t t1 , x0 t2 WHERE t1.id = t2.fatherID )
层次查询的结果如图：
2.动态行转列实现
有了组号，我们则根据同一组号的数据转到一行上展示。这里需要注意行转列的展示顺序，
排在前面的是子节点，后面是父节点。关于动态行转列的实现，可参考我前面的博客 将部分相同的多行记录转成一行多列。
SELECT id , name , level , ROW_NUMBER() OVER ( PARTITION BY level ORDER BY LEN(way) ) AS rn--节点的展示序号 INTO #t1 FROM x0 DECLARE @sql NVARCHAR(MAX); SET @sql = N'';SELECT @sql = @sql + ',max(case rn when ' + CAST(tt.rn AS VARCHAR) + ' then id end) ' + CASE WHEN rn = 1 THEN +'id' ELSE 'faterID' END + ',max(case rn when ' + CAST(tt.rn AS VARCHAR) + ' then name end) ' + CASE WHEN rn = 1 THEN +'name' ELSE 'faterName' ENDFROM ( SELECT DISTINCT rn FROM #t1 ) ttORDER BY rn;SET @sql = N'select level' + @sql + ' from #t1 group by level';EXEC(@sql);
（本文完）