Question

具有这样的数据

DECLARE @tbl TABLE (name1 varchar(5),name2 varchar(5),name3 varchar(5))
INSERT INTO @tbl(name1,name2,name3) 
values ('P1','A1','AA1'),('P1','B1','AA2'),('P1','C1','AA3'),('P1','A1','AA4')

输入表为：

name1   name2   name3
P1        A1    AA1
P1        B1    AA2
P1        C1    AA3
P1        A1    AA4

我想从这棵有点奇怪的树中选择，结果必须是这样的：

col1    col2
 P1      A1
 A1      AA1
 A1      AA4
 P1      B1
 B1      AA2
 P1      C1
 C1      AA4

第一行的示例'P1','A1','AA1' P1是A1的根，A1是AA1的根，而A1是{ AA4中的{1}}。这就是为什么输出必须像这样：

'P1','A1','AA4'

Sqlfiddle：http://www.sqlfiddle.com/#!18/87eb3/1

Answer 1

也许您想要的是这样的东西

SELECT col1, col2
FROM 
(
    SELECT name2 AS child, 0 AS type, name1 AS col1, name2 AS col2
    FROM @tbl

    UNION 

    SELECT name2 AS child, 1 AS type, name2 AS col1, name3 AS col2
    FROM @tbl
) AS t
ORDER BY child DESC, type, col1, col2

示例输出：

col1    col2
------------
P1      C1
C1      AA3
P1      B1
B1      AA2
P1      A1
A1      AA1
A1      AA4

如何从多列中选择树

1 个答案: