CTE 对祖父母的递归查询

Question

我关注table:

ID NAME PARENT_ID ISDELETED ISINEDIT
1  JJ     NULL     1          0
2  AR     1        0          0
3 PR      2        0          0
4 DR      NULL     0          1

我需要得到的是 SELECT 查询，该查询将 return 只有具有 ISDELETED 0 和 ISINEDIT 0 且其 parents 或 grandparents 为 0 的行嗯

我目前有：

;WITH ChildParent AS
(
    SELECT
        a.id,
        a.name,
        a.isinedit,
        a.parent_id,
        a.isdeleted
    FROM dbo.table 
    WHERE isdeleted = 0 AND isinedit = 0 

    UNION ALL

    SELECT
        a.id,
        a.name,
        a.isinedit,
        a.parent_id,
        a.isdeleted
    FROM dbo.table a
    INNER JOIN ChildParent cp ON a.parent_id = cp.id
    WHERE a.isdeleted = 0  AND a.isinedit = 0
)
SELECT  
        id,
        name,
    parent_id,
        isinedit,
        isdeleted
FROM ChildParent

但由于某种原因，它 return 是双行

Answer 1

您需要将相同的 isdeleted = 0 AND isinedit = 0 谓词添加到 INNER JOIN childParent CP 来源。

...但是，如果您这样做，您的 CTE 查询就会非常繁琐，如果您必须一遍又一遍地重复同样的事情，那么可能有更好的方法。

...还有！ SELECT 查询可以有多个 CTE 表达式：

;
WITH filtered AS
(
    SELECT
        a.id,
        a.name,
        a.parent_id,
    FROM
        dbo.Table
    WHERE
        IsDeleted = 0
        AND
        IsInEdit = 0 
)

WITH cte AS
(
    SELECT
        a.id,
        a.name,
        a.parent_id
    FROM
        filtered

    UNION ALL

    SELECT
        a.id,
        a.name,
        a.parent_id
    FROM
        filtered
        INNER JOIN cte ON a.parent_id = cte.id
)
SELECT  
    *
FROM
    cte
ORDER BY
    id

Answer 2

我认为这比您想象的要复杂一些。据我了解你的问题，你需要先遍历每个节点的整个 parent 层次结构，然后然后检查是否有任何 parent 不符合规则（你可以通过在满足第一个 non-compliant parent 后停止 来稍微优化它。

您还需要跟踪原始节点，以便您可以在外部查询中进行适当的过滤（这避免了您当前获得的重复项）。

我会将您的查询表述为：

with cte as ( select t.*, t.id original_id, 0 lvl, 1 is_ok from dbo.table t where isdeleted = 0 and isinedit = 0 union all select t.*, c.original_id, c.lvl + 1, case when t.isdeleted = 0 and t.isinedit = 0 then 1 else 0 end from dbo.table t inner join cte c on c.parent_id = t.id where c.is_ok = 1 ) select * from cte c where c.lvl = 0 and not exists ( select 1 from cte c1 where c1.original_id = c.original_id and c1.is_ok = 0 )

请注意，无论树中存在多少层，此查询都有效（如果层数超过 100 层，则需要在查询末尾添加 option(maxrecursion 0)。

Answer 3

如果您先在 CTE 中创建干净的数据集，这些类型的查询会更容易。它摆脱了所有 CTE 查询中的额外过滤子句。

在这种情况下，return 所有未删除且不在编辑中的行。接下来是获取数据 Grand Parent INNER JOIN Parent INNER JOIN CHILD

;WITH GoodDataRows AS
(
    SELECT
        a.id,
        a.name,
        a.isinedit,
        a.parent_id,
        a.isdeleted
    FROM dbo.table 
    WHERE isdeleted = 0 AND isinedit = 0 
)
SELECT
  *
FROM GoodDataRows gp
  INNER JOIN GoodDataRows p ON p.parent_id = gp.id
  INNER JOIN GoodDataRows c on c.parent_id = p.id

CTE 对祖父母的递归查询

CTE Recursive Query to Grandparents

sql

sql-server

select

subquery

recursive-query