Question

如何有人检索多个产品及其所有属性，这些属性的ID作为逗号分隔列表传递给存储过程？

表格采用简单的EAV方式设计，如下所示：

tbl_products
  id
  title

tbl_product_attributes
  product_FK
  attribute_FK
  attribute_value

tbl_attributes
  id
  title

以下存储过程仅针对一种产品执行此操作：

CREATE PROCEDURE get_product
  @product_id NVARCHAR(MAX)
AS
  BEGIN
    -- Create a temp table to store values of get_product_attributes sp
    CREATE TABLE #temp ( attributes NVARCHAR(MAX) );

    -- Insert results of get_product_attributes sp into temp table
    INSERT INTO #temp (attributes)
    EXEC get_product_attributes @product_id;

    -- Select product with all its attributes
    SELECT id,
           title,
           ( SELECT attributes FROM #temp ) AS attributes
    FROM   tbl_products
    WHERE  id = @product_id;
  END;

但是，如果我们想要产品ID的多个产品详细信息呢？

（get_product_attributes存储过程返回特定产品的所有属性及其值作为json，它使用动态sql检索所有属性，然后将它们作为json返回;完全类似于此答案的动态sql部分：https://stackoverflow.com/a/13092910/5048383）

（也使用sql server 2016，可以访问STRING_SPLIT函数，并且可以轻松地将传递的id转换为行）

Answer 1

一般来说，SQL中的循环很糟糕。对于你所描述的，我无法想象为什么它会保证循环。但是，这是一个基于集合的方法，只需要一个简单的连接就可以消除除了单个过程之外的所有内容。

declare @tbl_products table (
                            id int, 
                            title varchar(16))

insert into @tbl_products
values
(1,'prod1'),
(2,'prod2'),
(3,'prod3'),
(4,'prod4'),
(5,'prod5')

declare @tbl_attributes table (
                                id int,
                                title varchar(16))

insert into @tbl_attributes
values
(1,'attr1'),
(2,'attr2'),
(3,'attr3'),
(4,'attr4'),
(5,'attr5')


declare @tbl_product_attributes table (
                                        product_FK int,
                                        attribute_FK int,
                                        attribute_value varchar(64))

insert into @tbl_product_attributes
values
(1,5,'blah'),
(1,3,'blah blah'),
(2,1,'not sure'),
(2,3,'what should be here'),
(2,4,'but here is a'),
(3,5,'line of text'),
(3,4,'as a place holder')




declare @product_id nvarchar(4000)
set @product_id = '1,3'



if object_id ('tempdb..#staging') is not null
drop table #staging

select
    prod.id
    ,prod.title as ProductTitle
    ,'Attr' + cast(attr.id as char(8)) as AttributeID
    ,attr.title as AttributeTitle
    ,prodAttributes.attribute_value as EAV_AttributeValue
into #staging
from
    @tbl_products prod
inner join
    @tbl_product_attributes prodAttributes
    on prodAttributes.product_FK = prod.id
inner join
    @tbl_attributes attr on
    attr.id = prodAttributes.attribute_FK
inner join
    string_split(@product_id,',') x
    on x.value = prod.id




DECLARE @DynamicPivotQuery AS NVARCHAR(MAX)
DECLARE @ColumnName AS NVARCHAR(MAX)

--Get distinct values of the PIVOT Column 
SELECT @ColumnName= ISNULL(@ColumnName + ',','') 
       + QUOTENAME(AttributeID)
FROM (SELECT DISTINCT AttributeID FROM #staging) AS AttributeID


--Prepare the PIVOT query using the dynamic 
SET @DynamicPivotQuery = 
  N'
    SELECT ProductTitle,  ' + @ColumnName + '
    FROM #staging
    PIVOT(min(AttributeTitle) 
          FOR AttributeID IN (' + @ColumnName + ')) AS PVTTable'
--Execute the Dynamic Pivot Query
EXEC sp_executesql @DynamicPivotQuery

所以，你只需在顶部创建过程......

create proc yourProc(@product_id nvarchar(4000))
as

select
    prod.id
    ,prod.title as ProductTitle
    ,attr.title as AttributeTitle
    ,prodAttributes.attribute_value as EAV_AttributeValue
from
    @tbl_products prod
inner join
    @tbl_product_attributes prodAttributes
    on prodAttributes.product_FK = prod.id
inner join
    @tbl_attributes attr on
    attr.id = prodAttributes.attribute_FK
where
    prod.id in (select * from string_split(@product_id,','))

注意：这也可以作为连接更清晰地编写

select
    prod.id
    ,prod.title as ProductTitle
    ,attr.title as AttributeTitle
    ,prodAttributes.attribute_value as EAV_AttributeValue
from
    @tbl_products prod
inner join
    @tbl_product_attributes prodAttributes
    on prodAttributes.product_FK = prod.id
inner join
    @tbl_attributes attr on
    attr.id = prodAttributes.attribute_FK
inner join
    string_split(@product_id,',') x
    on x.value = prod.id

如何从EAV数据模型中检索具有所有属性的多个项目？

1 个答案: