仅显示唯一值

Question

我正在使用 SQL Server 2019，并正在寻找一种方法来根据每个 AOC 的最新 FW_Version 仅显示其最新值。这是我到目前为止的查询，但这显示了所有内容：

SELECT DISTINCT
    dbo.Model.ModelName AS AOC,
    dbo.Chipset.Chipset,
    dbo.FormFactor.FormFactor AS Form_Factor,
    dbo.ProductRelease.ECO AS Release,
    dbo.ProductRelease.Date AS Release_Date,
    dbo.Intel.FWVersion AS FW_Version,
    dbo.Intel.ETRACKID
FROM
    dbo.Intel
        INNER JOIN dbo.ProductRelease ON dbo.Intel.ProductReleaseID = dbo.ProductRelease.ID
        INNER JOIN dbo.Model ON dbo.ProductRelease.ModelID = dbo.Model.ID
        INNER JOIN dbo.FormFactor ON dbo.Model.FormFactorID = dbo.FormFactor.ID
        INNER JOIN dbo.Chipset ON dbo.Intel.ControllerID = dbo.Chipset.ControllerID AND dbo.Intel.ChipsetID = dbo.Chipset.ID
ORDER BY 
    dbo.Model.ModelName, 
    dbo.Intel.FWVersion DESC, 
    dbo.ProductRelease.Date DESC

我想只显示黄色标记的项目...我怎样才能做到这一点？

这是我的 Table 的列表，它们是根据相应的 ID

加入的

Table 1: 型号

ID (Primary Key)
ModelName nvarchar(50)
FormFactorID int

Table 2：外形尺寸

ID (Primary Key)
FormFactor nvarchar(15)

Table 3：产品发布

ID (Primary Key)
ModelID int
Date date
ECO nvarchar(10)

Table 4：英特尔

ID (Primary Key)
ProductReleaseID int
ChipsetID int
FWVersion nvarchar(10)
ETRACKID nvarchar(15)

Table 5: 芯片组

ID (Primary Key)
Chipsetnvarchar(20)

Answer 1

一种方法使用 window 函数：

SELECT *
FROM (
    SELECT 
        dbo.Model.ModelName AS AOC,
        dbo.Chipset.Chipset,
        dbo.FormFactor.FormFactor AS Form_Factor,
        dbo.ProductRelease.ECO AS Release,
        dbo.ProductRelease.Date AS Release_Date,
        dbo.Intel.FWVersion AS FW_Version,
        dbo.Intel.ETRACKID,
        ROW_NUMBER() OVER(PARTITION BY dbo.Model.ModelName ORDER BY dbo.ProductRelease.Date DESC) rn
    FROM
        dbo.Intel
        INNER JOIN dbo.ProductRelease ON dbo.Intel.ProductReleaseID = dbo.ProductRelease.ID
        INNER JOIN dbo.Model ON dbo.ProductRelease.ModelID = dbo.Model.ID
        INNER JOIN dbo.FormFactor ON dbo.Model.FormFactorID = dbo.FormFactor.ID
        INNER JOIN dbo.Chipset ON dbo.Intel.ControllerID = dbo.Chipset.ControllerID AND dbo.Intel.ChipsetID = dbo.Chipset.ID
) t
WHERE rn = 1
ORDER BY AOC

仅显示唯一值

Show Unique values only

sql

tsql

sql-server

greatest-n-per-group

sql-server-2019