SQL 自加入状态获胜者查询答案

【问题标题】：SQL Self Join Status Winner querySQL 自加入状态获胜者查询
【发布时间】：2016-10-01 10:22:04
【问题描述】：

我有一个具有自联接（父-子）的客户表，我需要编写一个查询来返回子客户，其中状态允许父或子下订单。该列是位列，可以为空。

返回的结果将基于以下矩阵：

parent_status   child_status    Child is allowed to Order
null                 null           FALSE
null                 0              FALSE
null                 1              TRUE
1                    null           TRUE
1                    1              TRUE
1                    0              FALSE
0                    null           FALSE
0                    1              FALSE
0                    0              FALSE

这里要求的是数据的架构和脚本

    CREATE TABLE [dbo].[Customer](
    [Customer_id] [int] NOT NULL,
    [ParentCustomer_id] [int] NULL,
    [Name_desc] [nvarchar](50) NULL,
    [OrderIsAllowed_status] [bit] NULL)
GO
insert Customer
([Customer_id],[ParentCustomer_id],[Name_desc] ,[OrderIsAllowed_status])
values(1,null,'Parent 1',1)
insert Customer
([Customer_id],[ParentCustomer_id],[Name_desc] ,[OrderIsAllowed_status])
values(2,1,'Parent 1 - Child 1',null)
insert Customer
([Customer_id],[ParentCustomer_id],[Name_desc] ,[OrderIsAllowed_status])
values(3,1,'Parent 1 - Child 2',0)
insert Customer
([Customer_id],[ParentCustomer_id],[Name_desc] ,[OrderIsAllowed_status])
values(4,1,'Parent 1 - Child 3',1)
insert Customer
([Customer_id],[ParentCustomer_id],[Name_desc] ,[OrderIsAllowed_status])
values(5,null,'Parent 2',null)
insert Customer
([Customer_id],[ParentCustomer_id],[Name_desc] ,[OrderIsAllowed_status])
values(6,5,'Parent 2 - Child 1',null)
insert Customer
([Customer_id],[ParentCustomer_id],[Name_desc] ,[OrderIsAllowed_status])
values(7,5,'Parent 2 - Child 2',1)
insert Customer
([Customer_id],[ParentCustomer_id],[Name_desc] ,[OrderIsAllowed_status])
values(8,5,'Parent 2 - Child 3',0)
insert Customer
([Customer_id],[ParentCustomer_id],[Name_desc] ,[OrderIsAllowed_status])
values(9,null,'Parent 3',0)
insert Customer
([Customer_id],[ParentCustomer_id],[Name_desc] ,[OrderIsAllowed_status])
values(10,9,'Parent 3 - Child 1',null)
insert Customer
([Customer_id],[ParentCustomer_id],[Name_desc] ,[OrderIsAllowed_status])
values(11,9,'Parent 3 - Child 2',1)
insert Customer
([Customer_id],[ParentCustomer_id],[Name_desc] ,[OrderIsAllowed_status])
values(12,9,'Parent 3 - Child 3',0)

【问题讨论】：

请添加您拥有的结构数据样本。到目前为止，您尝试过什么？
提供的信息不足，无法提供帮助。请提供其他示例数据/架构
道歉添加了一个架构和一些示例数据 - 只是认为这是一个足够简单的架构，看起来没有必要提供一个
你的预期输出是什么？

标签： sql-server hierarchy self-join

【解决方案1】：

根据真值表，CASE WHEN 如下所示。

该示例使用表变量仅用于演示。

declare @Customer table (Customer_id int NOT NULL, ParentCustomer_id int, OrderIsAllowed_status bit);

insert @Customer ([Customer_id], [ParentCustomer_id], [OrderIsAllowed_status]) values
(1,null,1),
(2,1,null),
(3,1,0),
(4,1,1),
(5,null,null),
(6,5,null),
(7,5,1),
(8,5,0),
(9,null,0),
(10,9,null),
(11,9,1),
(12,9,0);

select 
child.Customer_id, 
child.ParentCustomer_id,
(case 
 when child.ParentCustomer_id is null then 'Parent '+ cast(child.Customer_id as varchar)
 else concat('Parent ',parent.Customer_id,' - Child ',child.Customer_id)
 end) as Name_desc,
parent.OrderIsAllowed_status as parent_status,
child.OrderIsAllowed_status as child_status,
cast(case 
     when child.OrderIsAllowed_status = 1 and parent.OrderIsAllowed_status = 1 then 1
     when child.OrderIsAllowed_status = 1 and parent.OrderIsAllowed_status is null then 1
     when child.OrderIsAllowed_status is null and parent.OrderIsAllowed_status = 1 then 1
     else 0 
     end as bit) as [Child is allowed to Order]
from @Customer child
left join @Customer parent on (child.ParentCustomer_id = parent.Customer_id);

【讨论】：

感谢您的回答：我试图回答我自己的问题...以下语句有什么问题...选择 p.Customer_id ,p.Name_desc ,p.OrderIsAllowed_status as Parent_IsAllowed ,c .Customer_id ,c.ParentCustomer_id ,c.Name_desc ,c.OrderIsAllowed_status from Customer p 内部连接 Customer c on p.customer_id = c.ParentCustomer_id 其中 (p.OrderIsAllowed_status 为空且 c.OrderIsAllowed_status =1) 或 (p.OrderIsAllowed_status = 1并且 c.OrderIsAllowed_status 为空）或（p.OrderIsAllowed_status = 1 和 c.OrderIsAllowed_status = 1）
如果该 SQL 的目的是仅获取 [The child is allowed to order] 为 true 的那些 Children，那么该 SQL 没有错。虽然我个人是多对一的关系，但我会将“多”放入 from 并将“一”加入其中。

【解决方案2】：

您可以使用递归 CTE：

;WITH rec AS (
    SELECT  Customer_id,
            ParentCustomer_id,
            Name_desc,
            OrderIsAllowed_status,
            CAST(NULL AS bit) as parent_status,
            1 as [Level]
    FROM #Customer c
    WHERE ParentCustomer_id IS NULL
    UNION ALL
    SELECT  c.Customer_id,
            c.ParentCustomer_id,
            c.Name_desc,
            c.OrderIsAllowed_status,
            r.OrderIsAllowed_status,
            r.[Level]+ 1
    FROM rec r
    INNER JOIN #Customer c
        ON c.ParentCustomer_id = r.Customer_id
)

SELECT  r.Customer_id,
        r.ParentCustomer_id,
        r.Name_desc,
        r.OrderIsAllowed_status,
        rs.[Child is allowed to Order]
FROM rec r
INNER JOIN #rules rs
    ON COALESCE(r.[OrderIsAllowed_status],2) = COALESCE(rs.child_status,2)
        AND COALESCE(r.parent_status,2) = COALESCE(rs.parent_status,2)
WHERE r.ParentCustomer_id IS NOT NULL

输出：

Customer_id ParentCustomer_id   Name_desc           OrderIsAllowed_status   Child is allowed to Order
10          9                   Parent 3 - Child 1  NULL                    FALSE
11          9                   Parent 3 - Child 2  1                       FALSE
12          9                   Parent 3 - Child 3  0                       FALSE
6           5                   Parent 2 - Child 1  NULL                    FALSE
7           5                   Parent 2 - Child 2  1                       TRUE
8           5                   Parent 2 - Child 3  0                       FALSE
2           1                   Parent 1 - Child 1  NULL                    TRUE
3           1                   Parent 1 - Child 2  0                       FALSE
4           1                   Parent 1 - Child 3  1                       TRUE

我用过这个表：

CREATE TABLE #Customer (
    [Customer_id] [int] NOT NULL,
    [ParentCustomer_id] [int] NULL,
    [Name_desc] [nvarchar](50) NULL,
    [OrderIsAllowed_status] [bit] NULL
)

INSERT INTO #Customer VALUES
(1,null,'Parent 1',1),
(2,1,'Parent 1 - Child 1',null),
(3,1,'Parent 1 - Child 2',0),
(4,1,'Parent 1 - Child 3',1),
(5,null,'Parent 2',null),
(6,5,'Parent 2 - Child 1',null),
(7,5,'Parent 2 - Child 2',1),
(8,5,'Parent 2 - Child 3',0),
(9,null,'Parent 3',0),
(10,9,'Parent 3 - Child 1',null),
(11,9,'Parent 3 - Child 2',1),
(12,9,'Parent 3 - Child 3',0)

CREATE TABLE #rules (
    parent_status bit NULL,
    child_status bit NULL,
    [Child is allowed to Order] nvarchar(5) NULL
)

INSERT INTO #rules VALUES
(null, null, 'FALSE'),
(null, 0, 'FALSE'),
(null, 1, 'TRUE'),
(1, null, 'TRUE'),
(1, 1, 'TRUE'),
(1, 0, 'FALSE'),
(0, null, 'FALSE'),
(0, 1, 'FALSE'),
(0, 0, 'FALSE')

【讨论】：

【解决方案3】：

我已尝试回答我自己的问题...如果我只想退回允许下订单的儿童客户，那么以下问题会有什么问题：

 select p.Customer_id
    ,p.Name_desc
    ,p.OrderIsAllowed_status as Parent_IsAllowed
    ,c.Customer_id
    ,c.ParentCustomer_id
    ,c.Name_desc
    ,c.OrderIsAllowed_status    
from Customer p
inner join Customer c
    on p.customer_id = c.ParentCustomer_id
where 
    (p.OrderIsAllowed_status is null and c.OrderIsAllowed_status =1)
    or(p.OrderIsAllowed_status = 1 and c.OrderIsAllowed_status is null)
    or (p.OrderIsAllowed_status = 1 and c.OrderIsAllowed_status = 1)

【讨论】：

如果你有grandparent - parent - child，这将不起作用。
谢谢 - 我错过了这个场景..在我的案例中，表的历史用法只有一个层次结构 - 父 - 子，但你是对的我需要考虑原始设计
我的荣幸！ :)