SQL Server 树查询

Question

我需要一些帮助是 MS SQL Server 查询。我算不上什么DBA。我有一个带有组织表的应用程序，该表由父子关系组成：

CREATE TABLE [dbo].[Organizations](
    [OrgPK] [int] IDENTITY(1,1) NOT NULL,
    [OrgParentFK] [int] NULL,
    [OrgName] [varchar](200) NOT NULL,
CONSTRAINT [PK__Organizations] PRIMARY KEY CLUSTERED

示例数据如下所示：

OrgPK,   OrgParentFK, OrgName
1,  0,  Corporate
2,  1,  Department A
3,  1,  Department B
4,  2,  Division 1
5,  2,  Division 2
6,  3,  Division 1
7,  6,  Section 1
8,  6,  Section 2

我正在尝试生成一个查询，该查询返回基于给定 OrgPK 的组织路径。例如，如果给出 OrgPK = 7，则查询将返回“Corporation/Department B/Division 1/Section 1”

如果给出 OrgPk = 5，则返回字符串将为“Corporation/Department A/Division 2”

感谢您的帮助。

Answer 1

WITH  OrganizationsH (OrgParentFK, OrgPK, OrgName, level, Label) AS
(
    SELECT OrgParentFK, OrgPK, OrgName, 0, CAST(OrgName AS VARCHAR(MAX)) As Label
    FROM Organizations
    WHERE OrgParentFK IS NULL
    UNION ALL
    SELECT o.OrgParentFK, o.OrgPK, o.OrgName, level + 1,  CAST(h.Label + '/' + o.OrgName  VARCHAR(MAX)) As Label
    FROM Organizations o JOIN OrganizationsH h ON o.OrgParentFK = h.OrgPK
)

SELECT OrgParentFK, OrgPK, OrgName, level, Label
FROM OrganizationsH
WHERE OrgPK = 5

h/t 至 marc_s

Answer 2

也可以通过创建标量值函数来解决：

-- SELECT [dbo].[ListTree](5)
CREATE FUNCTION [dbo].[ListTree](@OrgPK int)
RETURNS varchar(max)
AS
BEGIN
    declare @Tree varchar(MAX)
    set @Tree = ''

    while(exists(select * from dbo.Organizations where OrgPK=@OrgPK))
    begin
        select  @Tree=OrgName+'/'+@Tree,
                @OrgPK=OrgParentFK
        from    dbo.Organizations
        where   OrgPK=@OrgPK

    end
    return  left(@Tree,len(@Tree)-1)
END