我需要按UniqueIdentifier
列進行分組,該表還包含XML列。如何按列分組 - SQL Server
表模式:StudentMark:
CREATE TABLE [dbo].[StudentMark]
(
[StudentMarkId] [int] IDENTITY(1,1) NOT NULL,
[StudentId] [uniqueidentifier] NULL,
[SubjectId] [uniqueidentifier] NULL,
[ScoreInfo] [xml] NULL,
[GeneratedOn] [datetime2](2) NOT NULL,
CONSTRAINT [PK_StudentMark]
PRIMARY KEY CLUSTERED ([StudentMarkId] ASC)
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
樣品種子數據
INSERT INTO [dbo].[StudentMark] ([StudentId], [SubjectId], [ScoreInfo], GeneratedOn])
VALUES ('FC3CB475-B480-4129-9190-6DE880E2D581', '0D72F79E-FB48-4D3E-9906-B78A9D105081', '<StudentMarkAttribute xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"></StudentMarkAttribute>', '2017-08-10 10:20:15'),
('0F4EF48C-93E3-41AA-8295-F6B0E8D8C3A2', '0D72F79E-FB48-4D3E-9906-B78A9D105081', '<StudentMarkAttribute xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"></StudentMarkAttribute>', '2017-08-10 10:20:15'),
('0F4EF48C-93E3-41AA-8295-F6B0E8D8C3A2', 'AB172272-D2E9-49E1-8040-6117BB6743DB', '<StudentMarkAttribute xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"></StudentMarkAttribute>', '2017-08-16 09:06:20'),
('FC3CB475-B480-4129-9190-6DE880E2D581', 'AB172272-D2E9-49E1-8040-6117BB6743DB', '<StudentMarkAttribute xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"></StudentMarkAttribute>', '2017-08-16 09:06:20');
要求:我需要按[dbo].[StudentMark].[StudentId]
採取的最新記錄。
我嘗試以下SQL查詢,但它造成的錯誤
SELECT
MAX([StudentMarkId]), [StudentId], [SubjectId], [ScoreInfo], [GeneratedOn]
FROM
[dbo].[StudentMark]
GROUP BY
[StudentId]
錯誤:
列「dbo.StudentMark.SubjectId」是因爲它是在選擇列表中無效不包含在聚合函數或GROUP BY子句中。
我審閱了以下問題,但我不能修復:Reason for Column is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause
請幫助我。
SELECT *
FROM (
SELECT *,
ROW_NUMBER() OVER(PARTITION BY StudentId ORDER BY StudentMarkId DESC) AS rn
FROM [dbo].[StudentMark]) sub
WHERE sub.rn = 1;
請您確認一下,我們不能使用「分組依據」?而不是'Row_Number'方法? –
@ B.Balamanigandan您不能以您建議的方式使用GROUP BY。你的問題很清楚,「每組最大的第n個」 – lad2025
你能否確認哪一個答案更可取?在優化方面的兩個答案? –