Question

我有3张桌子：

Productmaster：

ProductId    PName     PDescription

属性：

AttributeID  attName
----         ----
1            Brand
2            Category
3            Artist

ProductAttributeValues

paId   ProductId  AttributeID AttributeValues

product可以有多个attributes。

这是所需的输出：

ProductId  ProductDesc  Brand    Category    Artist
---        ---          ---      ---         ---
1          sadasd       Brand1   Category1   Artist1
2          sadasds      Brand2   Category3   Artist4

如何获得此输出？

提前致谢。

Answer 1

您应该为要引入的每个属性值保留连接，例如

select p.ProductId,p.ProductDesc,
a1.AttributeValues as Brand,
a2.AttributeValues as Category, 
a3.AttributeValues as Artist,
from Product p
left join ProductAttributeValues a1 on(p.ProductId=a1.ProductId and a1.AttributeID=1)
left join ProductAttributeValues a2 on(p.ProductId=a2.ProductId and a2.AttributeID=2)
left join ProductAttributeValues a3 on(p.ProductId=a3.ProductId and a3.AttributeID=3)

要把它变成英文，“给我所有产品，如果它们存在，给我一个品牌，类别和艺术家属性”

我假设产品每个属性只有一个或零值。

Answer 2

假设每个产品的每个属性只出现一次：

SELECT 
  pm.ProductId as ProductId,
  pm.PDescription as ProductDesc,
  pav_Brand.AttributeValues as Brand,
  pav_Category.AttributeValues as Category,
  pav_Artist.AttributeValues as Artist
FROM
  ProductMaster pm
    inner join ProductAttributeValues pav_Brand 
      on pm.productId == pav_Brand.ProductId
    inner join Attributes a_Brand 
      on pav_Brand.AttributeId = a_Brand.AttributeId
        AND a_Brand.attName = 'Brand'
    inner join ProductAttributeValues pav_Category 
      on pm.productId == pav_Category.ProductId
    inner join Attributes a_Category 
      on pav_Category.AttributeId = a_Category.AttributeId
        AND a_Brand.attName = 'Category'
    inner join ProductAttributeValues pav_Artist 
      on pm.productId == pav_Artist.ProductId
    inner join Attributes a_Artist 
      on pav_Category.AttributeId = a_Artist.AttributeId
        AND a_Brand.attName = 'Artist'

如果数据并非始终可用，则可以使用左外连接。

Answer 3

尝试此查询，可能需要一些调整

Select pm.ProductId, pm.PDescription, pav1.AttributeValues, pav2.AttributeValues, pav3.AttributeValues 
from Productmaster pm, ProductAttributeValues pav1, ProductAttributeValues pav2, ProductAttributeValues pav3 
where pm.ProductId = pav1.ProductId 
and pav1.AttributeID = 1 
and pm.ProductId = pav2.ProductId 
and pav2.AttributeID = 2 
and pm.ProductId = pav3.ProductId 
and pav3.AttributeID = 3

Answer 4

SELECT  ProductId, ProductDesc,
        (
        SELECT  AttributeValues
        FROM    ProductAttributeValues pv
        WHERE   pv.AttributeID = 1
                AND pv.ProductID = p.ProductID
        ) AS Brand,
        (
        SELECT  AttributeValues
        FROM    ProductAttributeValues pv
        WHERE   pv.AttributeID = 2
                AND pv.ProductID = p.ProductID
        ) AS Category,
        (
        SELECT  AttributeValues
        FROM    ProductAttributeValues pv
        WHERE   pv.AttributeID = 3
                AND pv.ProductID = p.ProductID
        ) AS Artist
FROM    Products p

SQL生成实体 - 属性 - 值结构化数据的报告

4 个答案: