我必须从这些表中提取数据
**PRODUCT** **LOOKUP_CATEGORY**
ID ProductName ID Category
1 Memory1 1 Product Type
2 Memory2 2 DIMM Type
3 Headset1 3 Color
4 Headset2 4 Speed
5 Keyboard1 5 Form Factor
6 Keyboard2
**LOOKUP**
ID CategoryID Value
1 1 DRAM
2 1 Keyboard
3 1 Headset
4 2 Buffered
5 2 Unbuffered
6 3 Red
7 3 White
8 3 Yellow
9 4 2000Mhz
10 4 2300Mhz
11 4 2600Mhz
12 5 DIMM
13 5 SODIMM
14 5 Earbud
15 5 On-Ear
**PRODUCT_FEATURES**
ID ProductID LookupID
1 1 1
2 1 4
3 1 10
4 1 12
5 2 1
6 2 5
7 2 9
8 2 13
9 3 3
10 3 7
11 3 15
12 4 3
13 4 6
14 4 14
15 5 2
16 5 7
17 6 2
18 6 8
我想要这样的结果集
ProductName Type DIMMType Color Speed FormFactor
Memory1 DRAM Buffered NULL 2300Mhz DIMM
Memory2 DRAM Unbuffered NULL 2000Mhz SODIMM
Headset1 Headset NULL White NULL On-Ear
Headset2 Headset NULL Red NULL Earbud
Keyboard1 Keyboard NULL White NULL NULL
Keyboard2 Keyboard NULL Yellow NULL NULL
基本上，我希望能够获得所有产品。 我如何不进行函数调用？我的数据库是Microsoft SQL 2016
我已经尝试过了，但是由于这些NULL值，它似乎无法正常工作
Select p.ProductID, p.ProductNumber
, lType.Value AS ProductType, lDimm.Value AS DimmType, lSpeed.Value AS Speed, lColor.Value AS Color, lFactor.Value AS FormFactor
From PRODUCT p
Left Join PRODUCT_FEATURES xType On p.ProductID = xType.ProductID
Inner Join LOOKUP lType On xType.LookupID = lType.LookupID
Inner Join LOOKUP_CATEGORY lcType On lType.CategoryID = lcType.LookupCategoryID And lcType.Category = 'Product Type'
Left Join PRODUCT_FEATURES xDimm On p.ProductID = xDimm.ProductID
Inner Join LOOKUP lDimm On xDimm.LookupID = lDimm.LookupID
Inner Join LOOKUP_CATEGORY lcDimm On lDimm.CategoryID = lcDimm.LookupCategoryID And lcDimm.Category = 'DIMM Type'
Left Join PRODUCT_FEATURES xSpeed On p.ProductID = xSpeed.ProductID
Inner Join LOOKUP lSpeed On xSpeed.LookupID = lSpeed.LookupID
Inner Join LOOKUP_CATEGORY lcSpeed On lSpeed.CategoryID = lcSpeed.LookupCategoryID And lcSpeed.Category = 'Speed'
Left Join PRODUCT_FEATURES xColor On p.ProductID = xColor.ProductID
Inner Join LOOKUP lColor On xColor.LookupID = lColor.LookupID
Inner Join LOOKUP_CATEGORY lcColor On lColor.CategoryID = lcColor.LookupCategoryID And lcColor.Category = 'Color'
Left Join PRODUCT_FEATURES xFactor On p.ProductID = xFactor.ProductID
Inner Join LOOKUP lFactor On xFactor.LookupID = lFactor.LookupID
Inner Join LOOKUP_CATEGORY lcFactor On lFactor.CategoryID = lcFactor.LookupCategoryID And lcFactor.Category = 'Form Factor'
答案 0 :(得分：1)
分组也许可以简化它。
SELECT
f.ProductID,
p.ProductName,
MAX(CASE WHEN lc.Category = 'Product Type' THEN l.Value END) AS ProductType,
MAX(CASE WHEN lc.Category = 'DIMM Type' THEN l.Value END) AS DimmType,
MAX(CASE WHEN lc.Category = 'Speed' THEN l.Value END) AS Speed,
MAX(CASE WHEN lc.Category = 'Color' THEN l.Value END) AS Color,
MAX(CASE WHEN lc.Category = 'Form Factor' THEN l.Value END) AS FormFactor
FROM PRODUCT_FEATURES f
LEFT JOIN PRODUCT p ON p.ID = f.ProductID
LEFT JOIN LOOKUP l ON l.ID = f.LookupID
LEFT JOIN LOOKUP_CATEGORY lc ON lc.ID = l.CategoryID
GROUP BY f.ProductID, p.ProductName
答案 1 :(得分：0)
您也可以如下编写它，如果您希望它真正是动态的，则必须使用动态SQL技术生成以下语句，请参见SQL Server dynamic PIVOT query?：
Select ProductId,
ProductName,
Test.[Product type],
Test.[DIMM Type],
Test.[Speed],
Test.[Color],
Test.[Form Factor]
From
(SELECT
P.ProductID,
p.ProductName,
Category,
value
FROM imp.PRODUCT_FEATURES f
LEFT JOIN imp.PRODUCT p ON p.productID = f.ProductID
LEFT JOIN imp.LOOKUP l ON l.lookupID = f.LookupID
LEFT JOIN imp.LOOKUP_CATEGORY lc ON lc.lookupcategoryID = l.CategoryID
) dt
pivot (max(dt.[value]) for dt.[CATEGORY] in ([Product type],[DIMM Type],[Speed],[Color],[Form Factor])) as test
为方便起见。 -首先创建模式IMP。.
/****** Object: Table [imp].[Lookup] Script Date: 8/1/2018 1:48:28 PM ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [imp].[Lookup](
[lookupID] [float] NULL,
[CategoryID] [float] NULL,
[Value] [nvarchar](255) NULL
) ON [PRIMARY]
GO
/****** Object: Table [imp].[Lookup_category] Script Date: 8/1/2018 1:48:28 PM ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [imp].[Lookup_category](
[lookupcategoryID] [float] NULL,
[Category] [nvarchar](255) NULL
) ON [PRIMARY]
GO
/****** Object: Table [imp].[Product] Script Date: 8/1/2018 1:48:28 PM ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [imp].[Product](
[ProductID] [float] NULL,
[ProductName] [nvarchar](255) NULL
) ON [PRIMARY]
GO
/****** Object: Table [imp].[Product_features] Script Date: 8/1/2018 1:48:28 PM ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [imp].[Product_features](
[ID] [float] NULL,
[ProductID] [float] NULL,
[LookupID] [float] NULL
) ON [PRIMARY]
GO
INSERT [imp].[Lookup] ([lookupID], [CategoryID], [Value]) VALUES (1, 1, N'DRAM')
GO
INSERT [imp].[Lookup] ([lookupID], [CategoryID], [Value]) VALUES (2, 1, N'Keyboard')
GO
INSERT [imp].[Lookup] ([lookupID], [CategoryID], [Value]) VALUES (3, 1, N'Headset')
GO
INSERT [imp].[Lookup] ([lookupID], [CategoryID], [Value]) VALUES (4, 2, N'Buffered')
GO
INSERT [imp].[Lookup] ([lookupID], [CategoryID], [Value]) VALUES (5, 2, N'Unbuffered')
GO
INSERT [imp].[Lookup] ([lookupID], [CategoryID], [Value]) VALUES (6, 3, N'Red')
GO
INSERT [imp].[Lookup] ([lookupID], [CategoryID], [Value]) VALUES (7, 3, N'White')
GO
INSERT [imp].[Lookup] ([lookupID], [CategoryID], [Value]) VALUES (8, 3, N'Yellow')
GO
INSERT [imp].[Lookup] ([lookupID], [CategoryID], [Value]) VALUES (9, 4, N'2000Mhz')
GO
INSERT [imp].[Lookup] ([lookupID], [CategoryID], [Value]) VALUES (10, 4, N'2300Mhz')
GO
INSERT [imp].[Lookup] ([lookupID], [CategoryID], [Value]) VALUES (11, 4, N'2600Mhz')
GO
INSERT [imp].[Lookup] ([lookupID], [CategoryID], [Value]) VALUES (12, 5, N'DIMM')
GO
INSERT [imp].[Lookup] ([lookupID], [CategoryID], [Value]) VALUES (13, 5, N'SODIMM')
GO
INSERT [imp].[Lookup] ([lookupID], [CategoryID], [Value]) VALUES (14, 5, N'Earbud')
GO
INSERT [imp].[Lookup] ([lookupID], [CategoryID], [Value]) VALUES (15, 5, N'On-Ear')
GO
INSERT [imp].[Lookup_category] ([lookupcategoryID], [Category]) VALUES (1, N'Product Type')
GO
INSERT [imp].[Lookup_category] ([lookupcategoryID], [Category]) VALUES (2, N'DIMM Type')
GO
INSERT [imp].[Lookup_category] ([lookupcategoryID], [Category]) VALUES (3, N'Color')
GO
INSERT [imp].[Lookup_category] ([lookupcategoryID], [Category]) VALUES (4, N'Speed')
GO
INSERT [imp].[Lookup_category] ([lookupcategoryID], [Category]) VALUES (5, N'Form Factor')
GO
INSERT [imp].[Product] ([ProductID], [ProductName]) VALUES (1, N'Memory1')
GO
INSERT [imp].[Product] ([ProductID], [ProductName]) VALUES (2, N'Memory2')
GO
INSERT [imp].[Product] ([ProductID], [ProductName]) VALUES (3, N'Headset1')
GO
INSERT [imp].[Product] ([ProductID], [ProductName]) VALUES (4, N'Headset2')
GO
INSERT [imp].[Product] ([ProductID], [ProductName]) VALUES (5, N'Keyboard1')
GO
INSERT [imp].[Product] ([ProductID], [ProductName]) VALUES (6, N'Keyboard2')
GO
INSERT [imp].[Product_features] ([ID], [ProductID], [LookupID]) VALUES (1, 1, 1)
GO
INSERT [imp].[Product_features] ([ID], [ProductID], [LookupID]) VALUES (2, 1, 4)
GO
INSERT [imp].[Product_features] ([ID], [ProductID], [LookupID]) VALUES (3, 1, 10)
GO
INSERT [imp].[Product_features] ([ID], [ProductID], [LookupID]) VALUES (4, 1, 12)
GO
INSERT [imp].[Product_features] ([ID], [ProductID], [LookupID]) VALUES (5, 2, 1)
GO
INSERT [imp].[Product_features] ([ID], [ProductID], [LookupID]) VALUES (6, 2, 5)
GO
INSERT [imp].[Product_features] ([ID], [ProductID], [LookupID]) VALUES (7, 2, 9)
GO
INSERT [imp].[Product_features] ([ID], [ProductID], [LookupID]) VALUES (8, 2, 13)
GO
INSERT [imp].[Product_features] ([ID], [ProductID], [LookupID]) VALUES (9, 3, 3)
GO
INSERT [imp].[Product_features] ([ID], [ProductID], [LookupID]) VALUES (10, 3, 7)
GO
INSERT [imp].[Product_features] ([ID], [ProductID], [LookupID]) VALUES (11, 3, 15)
GO
INSERT [imp].[Product_features] ([ID], [ProductID], [LookupID]) VALUES (12, 4, 3)
GO
INSERT [imp].[Product_features] ([ID], [ProductID], [LookupID]) VALUES (13, 4, 6)
GO
INSERT [imp].[Product_features] ([ID], [ProductID], [LookupID]) VALUES (14, 4, 14)
GO
INSERT [imp].[Product_features] ([ID], [ProductID], [LookupID]) VALUES (15, 5, 2)
GO
INSERT [imp].[Product_features] ([ID], [ProductID], [LookupID]) VALUES (16, 5, 7)
GO
INSERT [imp].[Product_features] ([ID], [ProductID], [LookupID]) VALUES (17, 6, 2)
GO
INSERT [imp].[Product_features] ([ID], [ProductID], [LookupID]) VALUES (18, 6, 8)
GO