INNER JOIN 和 Row_Num() 函数问题

Question

我有一个存储过程，它对 pnd 分页进行排序，如 对 Scott Michell 的自定义分页结果进行排序。

我有两个表：Article 和 Category。我的存储过程适用于 Article 表，但我想将 Category 表中的一列添加到查询中（我的意思是内部联接）。

实际上我不能像斯科特·米歇尔那样做，因为两个表中都有一些相似的列（当我一直喜欢斯科特时，我会得到“不明确的列错误”）。

我没有内部联接的存储过程是：

set ANSI_NULLS ON
set QUOTED_IDENTIFIER ON
go

ALTER PROCEDURE [dbo].[sp_Articles_SelectByCategoryId]
    @CategoryId int,
    @startRowIndex int = -1,
    @maximumRows int = -1,
    @sortExpression nvarchar(50),
    @recordCount int = NULL OUTPUT
AS
    IF (@recordCount IS NOT NULL)
    BEGIN
        SET @recordCount = (SELECT COUNT(*) 
                            FROM [dbo].[Articles] 
                            WHERE [CategoryId] = @CategoryId)
        RETURN
    END

    IF LEN(@sortExpression) = 0
       SET @sortExpression = 'Id'

    DECLARE @sql nvarchar(4000)

    SET @sql = 'SELECT [Id], [AddedDate], [AddedBy], [CategoryId],
                       [Title], [Abstract], [Body]
                FROM
                    (SELECT 
                         [Id], [AddedDate], [AddedBy], [CategoryId],
                         [Title], [Abstract], [Body],
                         ROW_NUMBER() OVER(ORDER BY ' + @sortExpression + ') as RowNum
                     FROM [dbo].[Articles]
                     WHERE CategoryId = ' + CONVERT(nvarchar(10), @CategoryId) + ') as CategoryIdInfo
         WHERE ((RowNum between (' + CONVERT(nvarchar(10), @startRowIndex) + ') AND ' + CONVERT(nvarchar(10), @startRowIndex) + ' + ' + CONVERT(nvarchar(10), @maximumRows) + ' - 1) 
   OR ' + CONVERT(nvarchar(10), @startRowIndex) + ' = -1 OR ' + CONVERT(nvarchar(10), @maximumRows) + ' = -1)'

      -- Execute the SQL query
      EXEC sp_executesql @sql

我的Category表是：

CREATE TABLE [dbo].[Category]
(
   [Id] [int] IDENTITY(1,1) NOT NULL,
   [AddedDate] [datetime] NOT NULL,
   [AddedBy] [nvarchar](250) COLLATE Arabic_CI_AS NOT NULL,
   [Title] [nvarchar](50) COLLATE Arabic_CI_AS NOT NULL,
   [Importance] [int] NOT NULL,
   [Description] [nvarchar](300) COLLATE Arabic_CI_AS NULL,
   [ImageUrl] [nvarchar](50) COLLATE Arabic_CI_AS NULL,

   CONSTRAINT [PK_Category] 
      PRIMARY KEY CLUSTERED ([Id] ASC)
)

我的Article表：

CREATE TABLE [dbo].[Articles]
(
    [Id] [int] IDENTITY(1,1) NOT NULL,
    [AddedDate] [datetime] NOT NULL,
    [AddedBy] [nvarchar](250) COLLATE Arabic_CI_AS NOT NULL,
    [CategoryId] [int] NOT NULL,
    [Title] [nvarchar](255) COLLATE Arabic_CI_AS NOT NULL,
    [Abstract] [nvarchar](4000) COLLATE Arabic_CI_AS NULL,
    [Body] [nvarchar](max) COLLATE Arabic_CI_AS NOT NULL,
    [ReleaseDate] [datetime] NULL,
    [ExpireDate] [datetime] NULL,
    [Approved] [bit] NOT NULL,
    [Listed] [bit] NOT NULL,
    [CommentEnabled] [bit] NOT NULL,
    [OnlyForMembers] [bit] NOT NULL,
    [ViewCount] [int] NOT NULL,
    [Votes] [int] NOT NULL,
    [TotalRating] [int] NOT NULL,
 CONSTRAINT [PK_Articles] PRIMARY KEY CLUSTERED 
(
    [Id] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]

我不知道如何将“Category”表的“Title”列添加到询问。

如果我的 Category 表没有类似的字段，那么此查询肯定有效：

DECLARE @sql nvarchar(4000)
SET @sql = 
'SELECT
    [Id],
    [AddedDate],
    [AddedBy],
    [CategoryId],
    [Title],
    [Abstract],
    [Body],
    ArticleTitle
FROM
    (SELECT 

    [Id],
    [AddedDate],
    [AddedBy],
    a.[CategoryId],
    [Title],
    [Abstract],
    [Body],
    b.Title as CategoryTitle ,
ROW_NUMBER() OVER(ORDER BY ' + @sortExpression + ') as RowNum

    FROM  [dbo].[Articles] a INNER JOIN Category b on a.CategoryId = b.Id

    WHERE a.CategoryId = ' + CONVERT(nvarchar(10), @CategoryId) + '
    ) as CategoryIdInfo

如果您想测试，可以下载 附件（表和 StoredProcedure） 谢谢

Answer 1

以下代码在您提供的表上完美运行 - 其中没有数据，但这应该不会产生影响，因为我只想证明查询执行，而不是结果。

此代码需要注意的事项：

排序表达式必须包含别名

SET @sortExpression = 'a.Id'       

所有重复列都必须有别名

请注意 a.[Id]、a.[AddedDate]、a.[Id]、a.[AddedDate]、a.[Id]、a.[AddedDate]、a. [AddedBy]、a.[CategoryId]、a.[Title]、b.[Title] 都是别名

内部和外部查询之间的列名称必须匹配

您的列名称为 ArticleTitle外部选择，而是内部选择中的一列 CategoryTitle 。那是行不通的。

DECLARE @SortExpression nvarchar(100)
SET @sortExpression = 'a.Id'        

DECLARE @sql nvarchar(4000) 
SET @sql =  
'SELECT 
    [Id], 
    [AddedDate], 
    [AddedBy], 
    [CategoryId], 
    [Title], 
    [Abstract], 
    [Body], 
    CategoryTitle 
FROM 
    (SELECT  

    a.[Id], 
    a.[AddedDate], 
    a.[AddedBy], 
    a.[CategoryId], 
    a.[Title], 
    [Abstract], 
    [Body], 
    b.Title as CategoryTitle , 
ROW_NUMBER() OVER(ORDER BY ' + @sortExpression + ') as RowNum 

    FROM  [dbo].[Articles] a INNER JOIN Category b on a.CategoryId = b.Id 

    WHERE a.CategoryId = ' + CONVERT(nvarchar(10), @CategoryId) + ' 
    ) as CategoryIdInfo' 

      -- Execute the SQL query 
  EXEC sp_executesql @sql  

Answer 2

您是否尝试过类似下面的代码？

这使用 AS 关键字为子查询中的列提供唯一的名称，并使用别名来允许对子查询连接本身中的列进行明确的引用。

另请注意，所有对不明确列的引用必须是别名，这包括您动态注入的 @sortExpression。

ALTER PROCEDURE [dbo].[sp_Articles_SelectByCategoryId]   
 @CategoryId int,   
 @startRowIndex int = -1,   
 @maximumRows int = -1,   
 @sortExpression nvarchar(50),   
 @recordCount int = NULL OUTPUT   

AS   

IF (@recordCount IS NOT NULL)   
 BEGIN   
  SET @recordCount = (SELECT COUNT(*) FROM [dbo].[Articles] WHERE [CategoryId] = @CategoryId   
 )   
  RETURN   
 END   

IF LEN(@sortExpression) = 0   
   SET @sortExpression = 'Id'

DECLARE @sql nvarchar(4000) 
SET @sql =  
'SELECT 
 [Id], 
 [AddedDate], 
 [AddedBy], 
 [CategoryId], 
 [Title], 
 -- CategoryTitle refers to the column name declared by that AS inside the subquery
 CategoryTitle
 [Abstract], 
 [Body], 

FROM 
 (SELECT  

 [Id], 
 [AddedDate], 
 [AddedBy], 
 -- The column aliases a and c allow us to refer to similarly names column unambiguously
 a.[CategoryId], 
 a.[Title], 
 c.[Title] as CategoryTitle,
 [Abstract], 
 [Body], 

--- This now includes an alias on the sortExpression order by
ROW_NUMBER() OVER(ORDER BY a.' + @sortExpression + ') as RowNum 

 FROM  [dbo].[Articles] a
 Join [dbo].[Category] c
 ON c.CategoryID = a.CategoryID
 WHERE c.CategoryId = ' + CONVERT(nvarchar(10), @CategoryId) + '

 ) as CategoryIdInfo 
 WHERE  
 ((RowNum between (' + CONVERT(nvarchar(10), @startRowIndex) + ') AND ' + CONVERT(nvarchar(10), @startRowIndex) + ' + ' + CONVERT(nvarchar(10), @maximumRows) + ' - 1)  
   OR ' + CONVERT(nvarchar(10), @startRowIndex) + ' = -1 OR ' + CONVERT(nvarchar(10), @maximumRows) + ' = -1)' 

  -- Execute the SQL query 
  EXEC sp_executesql @sql 

其作用是为 Articles 和 Category 表（分别为 a 和 c）声明一个别名，允许您明确地引用它们的列。

我还没有尝试过使用 Row_Number 的确切情况，但想不出它不起作用的原因。

然后使用 AS 关键字应该为您提供一个与外部选择一起使用的唯一名称。