sql-server - 消除连接字符串中的重复项

Question

我有一个将多个记录连接到一个字段中的有效解决方案，但是我想从连接的字段中删除重复项，并按另一个字段对值进行排序。

这是我的:

CREATE VIEW vwImageDescriptions AS
    SELECT i.ItemId, STUFF(ImageDescriptions.line,1,2,'') AS ImageDescriptions
    FROM InventoryItems i
    CROSS APPLY (
        SELECT DISTINCT CAST((select CASE When p.Description = '' or p.Description is null Then '' Else '; ' + p.Description END
        FROM Photos p
        WHERE p.ItemId = i.ItemId
        ORDER BY p.Sequence
        FOR XML PATH('')) AS nvarchar(max)) line
    ) ImageDescriptions
go

select i.ItemName, id.ImageDescriptions
FROM InventoryItems i join vwImageDescriptions id on i.ItemId = id.ItemId
where id.ImageDescriptions like '%pla%'

这是我的结果:

我想要的是不要有重复的图像描述，例如，我希望在出现的每一行中只看到一次“我的图像”，而不是两次。如您所见，我在我的代码中使用了 DISTINCT，但这似乎不起作用。

这里是非常简化的 DDL 来查看问题:

DROP TABLE IF EXISTS [InventoryItems]
DROP TABLE IF EXISTS Photos
GO
CREATE TABLE [dbo].[InventoryItems](
    [ItemId] [int] NOT NULL,
    [ItemName] [varchar](100) NOT NULL
) ON [PRIMARY]
GO

CREATE TABLE [dbo].[Photos](
    [ItemId] [int] NOT NULL,
    [Description] [varchar](175) NULL,
    [Sequence] [int] NOT NULL
) ON [PRIMARY]
GO

INSERT INTO [InventoryItems]([ItemId],[ItemName]) VALUES(311,'11" Round Vegetable Bowl');
INSERT INTO [InventoryItems]([ItemId],[ItemName]) VALUES(312,'13" Oval Serving Platter');
INSERT INTO [InventoryItems]([ItemId],[ItemName]) VALUES(313,'19" Oval Serving Platter');
INSERT INTO [InventoryItems]([ItemId],[ItemName]) VALUES(314,'Creamer');
INSERT INTO [InventoryItems]([ItemId],[ItemName]) VALUES(315,'Gravy Boat with Attached Underplate');
INSERT INTO [InventoryItems]([ItemId],[ItemName]) VALUES(317,'Round Butter Dish and Lid');
INSERT INTO [InventoryItems]([ItemId],[ItemName]) VALUES(318,'Sugar Bowl and Lid');
INSERT INTO [InventoryItems]([ItemId],[ItemName]) VALUES(319,'Vegetable Server Bowl and Lid');

INSERT INTO [Photos]([ItemId],[Description],[Sequence])VALUES(311,'',1)
INSERT INTO [Photos]([ItemId],[Description],[Sequence])VALUES(312,'Replacements.com image',1)
INSERT INTO [Photos]([ItemId],[Description],[Sequence])VALUES(313,'Replacements.com image',1)
INSERT INTO [Photos]([ItemId],[Description],[Sequence])VALUES(313,'Outer platter is the 19"',2)
INSERT INTO [Photos]([ItemId],[Description],[Sequence])VALUES(313,'Outer platter is the 19"',3)
INSERT INTO [Photos]([ItemId],[Description],[Sequence])VALUES(313,'Outer platter is the 19"',4)
INSERT INTO [Photos]([ItemId],[Description],[Sequence])VALUES(313,'Another image',5)
INSERT INTO [Photos]([ItemId],[Description],[Sequence])VALUES(314,'Replacements.com image',1)
INSERT INTO [Photos]([ItemId],[Description],[Sequence])VALUES(315,'From replacements.com',1)
INSERT INTO [Photos]([ItemId],[Description],[Sequence])VALUES(315,'My image',2)
INSERT INTO [Photos]([ItemId],[Description],[Sequence])VALUES(315,'My image',3)
INSERT INTO [Photos]([ItemId],[Description],[Sequence])VALUES(315,'My image',4)
INSERT INTO [Photos]([ItemId],[Description],[Sequence])VALUES(316,'My image',1)
INSERT INTO [Photos]([ItemId],[Description],[Sequence])VALUES(316,'My image',2)
INSERT INTO [Photos]([ItemId],[Description],[Sequence])VALUES(316,'From replacements.com',3)

Answer 1

我认为这可以简化一点。据我了解所需的结果，这应该会产生您正在寻找的结果。非常感谢您提供表格和示例数据。

select i.ItemId
    , ImageDescriptions = isnull(STUFF((select ',' + isnull(p.Description, '')
            from Photos p
            where p.ItemId = i.ItemId
            group by isnull(p.Description, '')
            order by min(p.Sequence)
            for xml path('')), 1, 1, ''), '')
FROM InventoryItems i
group by i.ItemId

--编辑--

就像我说的，CROSS APPLY 是一层这里不需要的复杂性。但这应该做同样的事情。

select i.ItemId
    , ImageDescriptions = isnull(x.asdf, '')
FROM InventoryItems i
cross apply
(
    select asdf = STUFF((select ',' + isnull(p.Description, '')
            from Photos p
            where p.ItemId = i.ItemId
            group by isnull(p.Description, '')
            order by min(p.Sequence)
            for xml path('')), 1, 1, '')
) x