在 Sql 中使用分区分组

Question

我有一个简单的table

CREATE TABLE [dbo].[Tooling](
[Id] [int] IDENTITY(1,1) NOT NULL,
[Name] [nvarchar](50) NOT NULL,
[Status] [int] NOT NULL,
[DateFinished] [datetime] NULL,
[Tooling] [nvarchar](50) NULL,
[Updated] [datetime] NULL,

 ) ON [PRIMARY]

具有以下值

SET IDENTITY_INSERT [dbo].[Tooling] ON 

GO
INSERT [dbo].[Tooling] ([Id], [Name], [Status], [DateFinished], [Tooling], [Updated]) VALUES (1, N'Large', 0, NULL, NULL, CAST(N'2015-05-05 00:00:00.000' AS DateTime))
GO
INSERT [dbo].[Tooling] ([Id], [Name], [Status], [DateFinished], [Tooling], [Updated]) VALUES (2, N'Large', 1, NULL, N'1', CAST(N'2015-05-10 00:00:00.000' AS DateTime))
GO
INSERT [dbo].[Tooling] ([Id], [Name], [Status], [DateFinished], [Tooling], [Updated]) VALUES (3, N'Small', 0, NULL, N'2', CAST(N'2015-05-11 00:00:00.000' AS DateTime))
GO
INSERT [dbo].[Tooling] ([Id], [Name], [Status], [DateFinished], [Tooling], [Updated]) VALUES (4, N'Large', 2, NULL, N'1', CAST(N'2015-05-12 00:00:00.000' AS DateTime))
GO
INSERT [dbo].[Tooling] ([Id], [Name], [Status], [DateFinished], [Tooling], [Updated]) VALUES (5, N'Large', 2, NULL, N'2', CAST(N'2015-05-12 00:00:00.000' AS DateTime))
GO
INSERT [dbo].[Tooling] ([Id], [Name], [Status], [DateFinished], [Tooling], [Updated]) VALUES (6, N'Large', 1, NULL, N'1', CAST(N'2015-05-13 00:00:00.000' AS DateTime))
GO
INSERT [dbo].[Tooling] ([Id], [Name], [Status], [DateFinished], [Tooling], [Updated]) VALUES (7, N'Large', 1, NULL, N'2', CAST(N'2015-05-14 00:00:00.000' AS DateTime))
GO
INSERT [dbo].[Tooling] ([Id], [Name], [Status], [DateFinished], [Tooling], [Updated]) VALUES (8, N'Small', 1, CAST(N'2015-05-15 00:00:00.000' AS DateTime), N'2', CAST(N'2015-05-15 00:00:00.000' AS DateTime))
GO
SET IDENTITY_INSERT [dbo].[Tooling] OFF

我想创建一个 table 的视图，它看起来像是一个完全属于自己的 table。

SELECT         Id, Name, Status, DateFinished
FROM          Tooling t order by t.id

如果我运行我希望排除 ID 为 5 和 7 的记录，因为它们不会在上一行的选定集中发生变化。我有一个想法通过在分区上使用 ROW_NUMBER() 来解决这个问题并通过使用 group by 但这似乎不正确（根本无法让它工作）

当应该根据值的变化而不是它包含的值进行分组时，我如何对其进行分组？有什么建议可以解决这个问题吗？我的最终目标也是尝试将其转换为 linq to entities...

Answer 1

好的，假设它是按id排序的

select * 
from (
  select *, rng = row_number() over (partition by grp order by id)
  from (
    select *, grp = row_number() over (order by id) - row_number() over (partition by Name, Status, DateFinished order by id)
    from tooling ) g
  ) gn
where rng = 1
order by id

在 Sql 中使用分区分组

Grouping with partition and over in TSql

sql

tsql

group-by

rowcount

window-functions