如何在T-SQL中使用递归CTE获得完整的层次结构？

Posted 2023-01-07

表格：

+-----+------------+-------------+
| Id  | DocumentNo | ParentCCID  |
+-----+------------+-------------+
|  10 | CC001      | NULL        |
|  20 | CC002      | CC001       |
|  33 | CC003      | CC002       |
+-----+-------------+-------------+

传递给查询的值：CC002

预期输出：

CC003
CC002
CC001

以下查询仅使您获得在层次结构中置于较高位置的记录：

;WITH cte AS (
        SELECT Id,
            documentno,
            DocumentTypeID,
            ParentCCID
        FROM basicdetails
        WHERE DocumentNo = 'CC#000056'

        UNION ALL

        SELECT R.Id,
            R.DocumentNo,
            R.DocumentTypeID,
            R.ParentCCID
        FROM basicdetails R
        JOIN cte P ON P.ParentCCID = R.DocumentNo
        )

SELECT Id,
    documentno,     
    ParentCCID
FROM cte
ORDER BY 1 DESC

注意：DocumentNo是唯一的主键。如果没有父记录，则ParentCCID可以为空值。

create table basicdetails
  (
    id int identity,
    documentno varchar(30),
    parentccid varchar(30)
  )
    insert into basicdetails values('CC001', null)
    insert into basicdetails values('CC002', 'CC001')
    insert into basicdetails values('CC003', 'CC002')
    insert into basicdetails values('CC004', 'CC003')

答案

我想我找到了答案。

;WITH cte AS (
        SELECT Id,
            documentno,
            DocumentTypeID,
            ParentCCID
        FROM basicdetails
        WHERE DocumentNo = 'CC02'

        UNION ALL

        SELECT R.Id,
            R.DocumentNo,
            R.DocumentTypeID,
            R.ParentCCID
        FROM basicdetails R
        JOIN cte P ON P.ParentCCID = R.DocumentNo
        ),

      cte2 AS (
        SELECT Id,
            documentno,
            DocumentTypeID,
            ParentCCID
        FROM basicdetails
        WHERE DocumentNo = 'CC002'

        UNION ALL

        SELECT R.Id,
            R.DocumentNo,
            R.DocumentTypeID,
            R.ParentCCID
        FROM basicdetails R
        JOIN cte2 P ON P.DocumentNo = R.ParentCCID
        )


SELECT Id,
    documentno,
    DocumentTypeID,
    ParentCCID
FROM cte     

 union   

SELECT Id,
    documentno,
    DocumentTypeID,
    ParentCCID
FROM cte2    

尽管我不确定这是否是最好的方法。确实有效。我只需要扭转JOIN cte P ON P.ParentCCID = R.DocumentNo并执行UNION