sql - 将相同的 SNo 分配给父级及其子级

Question

我有一个名为“TmpTable”的表，该表具有父子关系，表的数据如下所示：

Id | Name      | ParentId
 1   PCs         0
 2   MACs        1
 3   Keyboard    0
 4   Mouse       0
 5   Screen      3
 6   Keyboard    4
 7   Mouse       0
 8   Screen      0
 9   Key         0          
 10  xyz         9          

现在我想选择一列显示序列号，在那个父和子有相同的 S.No. 并且没有孩子的S.No.增加，结果如下：

Id | Name      | ParentId | SNo
 1   PCs         0           1  
 2   MACs        1           1
 3   Keyboard    0           2
 4   Mouse       0           3
 5   Screen      3           2
 6   Keyboard    4           3
 7   Mouse       0           4
 8   Screen      0           5
 9   Key         0           6
 10  xyz         9           6

我该如何存档这个结果，请指导/帮助我。

Answer 1

您可以DENSE_RANK()结合使用函数ORDER BY CASE：

SELECT *, DENSE_RANK() OVER (ORDER BY CASE WHEN ParentID = 0 THEN ID ELSE ParentID END) 
FROM TmpTable
ORDER BY Id

SQLFiddle 演示

Answer 2

你可以这样试试。

;with cte as 
(Select Row_Number() Over(Order by Id) as Row,Id from Table1 where Parentid=0
)
Select A.*,b.row as Sno from Table1 A inner join
cte as b on b.id=a.parentid or (b.id=a.id and a.parentid=0) order by a.id;

Sql 小提琴演示

Answer 3

这是 n 深度的完整解决方案：

;WITH src AS (
    SELECT id=1, pid=0
    UNION ALL SELECT id=2, pid=1
    UNION ALL SELECT id=3, pid=0
    UNION ALL SELECT id=4, pid=0
    UNION ALL SELECT id=5, pid=3
    UNION ALL SELECT id=6, pid=4
    UNION ALL SELECT id=7, pid=0
    UNION ALL SELECT id=8, pid=0
    UNION ALL SELECT id=9, pid=0
    UNION ALL SELECT id=10, pid=9
),
rcte AS (
    SELECT id, pid, sno = ROW_NUMBER() OVER (ORDER BY id) 
    FROM src WHERE pid=0
    UNION ALL
    SELECT s.id, s.pid, r.sno
    FROM 
        rcte r
        JOIN src s 
            ON s.pid = r.id
    WHERE s.pid != 0 
)
SELECT *
FROM rcte
ORDER BY id

Answer 4

这也可以通过JOIN. 我认为这可能对 MYSQL 有帮助，因为它没有窗口函数

SELECT 
  DISTINCT 
  m1.id,
  m1.name,
  m1.parentid,
  1 + count( m2.id ) as sno
FROM
  mytable m1 
  LEFT JOIN mytable m2 on ( ( m1.parentid = 0 AND m2.parentid = 0 AND m2.id < m1.id)
                              OR ( m2.parentid = 0 AND m2.id < m1.parentid ) )
GROUP BY
  m1.id,
  m1.name,
  m1.parentid

SQLFIDDLE

注意：它假设你的父母总是id比他们的childs