SQL Server 2008 - Concatenate字符串

Question

我需要对每个行项目进行查询的结果,并构建一个以分号分隔的构成该项目的材料列表.

架构化妆:

表:LineItems(唯一项目清单)LineItems_Materials(多对多)材料(唯一材料清单)

行项目:ID | LineItem 1 |'1A.1'

LineItems_Materials:ID | LineItemID | MaterialID 1 | 1 | 1 2 | 1 | 2 3 | 1 | 3

材料:ID |材料1 |混凝土2 |钢3 |污垢

因此,对于第1项(1A.1)项,我希望它显示混凝土;钢;污垢

我知道我可以写一个函数来做到这一点.我在函数中使用了CTE ....我也可以使用while循环.还有另一种方法会更好吗？

这就是我所拥有的(脚本将构建对象,加载数据和创建函数):

SCRIPT:
    IF  EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[test].[UFN_LineItem_Materials]') AND type in (N'FN', N'IF', N'TF', N'FS', N'FT'))
    DROP FUNCTION [test].[UFN_LineItem_Materials]
    GO
    IF  EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[test].[LineItems]') AND type in (N'U'))
    DROP TABLE [test].[LineItems]
    GO
    IF  EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[test].[Materials]') AND type in (N'U'))
    DROP TABLE [test].[Materials]
    GO
    IF  EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[test].[LineItems_Materials]') AND type in (N'U'))
    DROP TABLE [test].[LineItems_Materials]
    GO
    IF  EXISTS (SELECT * FROM sys.schemas WHERE name = N'test')
    DROP SCHEMA [test]
    GO
    CREATE SCHEMA [test] AUTHORIZATION [dbo]
    GO

    Create Table test.Materials(
    MaterialID  INT IDENTITY(1,1),
    Material varchar(100));

    Insert Into test.Materials
    Values('Concrete');


    Insert Into test.Materials
    Values('Steel');


    Insert Into test.Materials
    Values('Dirt');

    GO
    Create Table test.LineItems_Materials(
    LineItemMaterialID  INT IDENTITY(1,1),
    LineItemID          INT,
    MaterialID          INT)

    GO

    Insert Into test.LineItems_Materials
    Select 1,1
    UNION
    Select 1,2
    UNION
    Select 1,3


    GO


    CREATE TABLE [test].[LineItems](
        [LineItemID] [int] IDENTITY(1,1) NOT NULL,
        [ItemNumber] [varchar](25) NULL
    ) ON [PRIMARY]

    GO

    Insert Into [test].[LineItems]
    Select '1A.1'


    GO
    -------------------------------------------------------------
    --Build Material Strings (;) example: List of Materials
    ------------------------------------------------------------

    CREATE FUNCTION test.UFN_LineItem_Materials(@LineItemID INT)
        RETURNS VARCHAR(100)
    AS

    BEGIN

        DECLARE @Materials Varchar(100) = ''
        ;with CTE
        AS(
        Select lm.LineItemID,m.MaterialID,m.Material
        from test.LineItems_Materials lm
        inner join test.Materials m on lm.MaterialID = m.MaterialID
        Where lm.LineItemID = @LineItemID
        )
        Select @Materials += ';' + c.Material
        from CTE c;

        SET @Materials = substring(@Materials,2,LEN(@Materials)-1);

        RETURN @Materials;

    END
    GO

    Select lm.LineItemID,test.UFN_LineItem_Materials(lm.LineItemID) Materials
    From test.Materials m
    inner join test.LineItems_Materials lm on m.MaterialID = lm.MaterialID
    Where m.Material = 'Concrete'

还有其他想法吗？

总是欣赏反馈

--S

Answer 1

如果要跨行连接值,请使用FOR XML技巧,例如:

SELECT Name + ',' 
FROM Project
FOR XML PATH('') 

这是一个更完整的例子:

select LineItemID, (
        Select m.Material + ','
        From test.Materials m 
        inner join test.LineItems_Materials lm1 on m.MaterialID = lm1.MaterialID 
        Where m.MaterialID in (select MaterialID from test.LineItems_Materials where LineItemID = lm2.LineItemID)
        FOR XML PATH('')  
    ) as Materials
from test.LineItems_Materials lm2
group by LineItemID