SQL Server : How to create hierarchy combinations from a table

Question

我将层次结构的级别堆叠在一个表中，并且我想创建组合。我尝试使用递归查询，但我无法弄清楚。我确信一定有一种简单的方法可以做到这一点。我有不同的层次结构和不同的级别数，因此我不想为每个层次结构编写代码，而是希望有一个处理级别数的查询。我将不胜感激任何帮助!

以下是创建示例数据的代码:

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [tmp].[tblSample](
    [hier] [nvarchar](255) NULL,
    [lvl] [nvarchar](255) NULL,
    [id] [int] NULL
) ON [PRIMARY]
GO
INSERT [tmp].[tblSample] ([hier], [lvl], [id]) VALUES (N'AA00010102', N'3', 3)
GO
INSERT [tmp].[tblSample] ([hier], [lvl], [id]) VALUES (N'AA00019999', N'3', 4)
GO
INSERT [tmp].[tblSample] ([hier], [lvl], [id]) VALUES (N'AA00020107', N'3', 6)
GO
INSERT [tmp].[tblSample] ([hier], [lvl], [id]) VALUES (N'AA00029999', N'3', 7)
GO
INSERT [tmp].[tblSample] ([hier], [lvl], [id]) VALUES (N'AA11810001', N'3', 9)
GO
INSERT [tmp].[tblSample] ([hier], [lvl], [id]) VALUES (N'AA11812087', N'3', 10)
GO
INSERT [tmp].[tblSample] ([hier], [lvl], [id]) VALUES (N'AA11852299', N'3', 12)
GO
INSERT [tmp].[tblSample] ([hier], [lvl], [id]) VALUES (N'AA1185', N'2', 12)
GO
INSERT [tmp].[tblSample] ([hier], [lvl], [id]) VALUES (N'AA', N'1', 12)
GO
INSERT [tmp].[tblSample] ([hier], [lvl], [id]) VALUES (N'AA1181', N'2', 10)
GO
INSERT [tmp].[tblSample] ([hier], [lvl], [id]) VALUES (N'AA', N'1', 10)
GO
INSERT [tmp].[tblSample] ([hier], [lvl], [id]) VALUES (N'AA1181', N'2', 9)
GO
INSERT [tmp].[tblSample] ([hier], [lvl], [id]) VALUES (N'AA', N'1', 9)
GO
INSERT [tmp].[tblSample] ([hier], [lvl], [id]) VALUES (N'AA0002', N'2', 7)
GO
INSERT [tmp].[tblSample] ([hier], [lvl], [id]) VALUES (N'AA', N'1', 7)
GO
INSERT [tmp].[tblSample] ([hier], [lvl], [id]) VALUES (N'AA0002', N'2', 6)
GO
INSERT [tmp].[tblSample] ([hier], [lvl], [id]) VALUES (N'AA', N'1', 6)
GO
INSERT [tmp].[tblSample] ([hier], [lvl], [id]) VALUES (N'AA0001', N'2', 4)
GO
INSERT [tmp].[tblSample] ([hier], [lvl], [id]) VALUES (N'AA', N'1', 4)
GO
INSERT [tmp].[tblSample] ([hier], [lvl], [id]) VALUES (N'AA0001', N'2', 3)
GO
INSERT [tmp].[tblSample] ([hier], [lvl], [id]) VALUES (N'AA', N'1', 3)
GO

这是我为这个特定层次结构生成所需结果的查询:

SELECT t1.hier, t2.hier, t3.hier FROM tblSample t1 
    INNER JOIN tblSample t2 ON t1.id=t2.id AND t2.lvl=t1.lvl+1 
    INNER JOIN tblSample t3 ON t1.id=t3.id  AND t3.lvl=t1.lvl+2

示例数据:

期望结果:

Answer 1

这对我来说看起来就像条件聚合:

select max(case when lvl = 1 then hier end),
       max(case when lvl = 2 then hier end),
       max(case when lvl = 3 then hier end)
from tblSample
group by id;

或者，您可以将其表述为联接:

select s.hier, s2.hier, s3.hier
from tblSample s join
     tblSample s2
     on s2.lvl = s.lvl + 1 and
        s2.id = s.id join
     tblSample s3
     on s3.lvl = s2.lvl + 1 and
        s3.id = s2.id
where s.lvl = 1;

Here是一个数据库<> fiddle 。