将SQL查询合并为相似的结果

Question

我现在有一个系统存储与每个产品关联的产品和标签。

例

产品：话筒

标签：音乐，电子，音响

有一个标签表，产品列表，并TagProductMapping表。第三张表格显然将产品映射到标签以获得一对多的关系。当我使用LEFT JOIN查询Microphone产品时，我得到3条记录几乎是重复的，除了“TagName”列之外，显然它有3个不同的标签。我怎样才能合并这个结果？它令人沮丧，因为如果我试图精确地查询10个产品，它将仅限于10个结果，这不会是10个产品。

任何人都有这个好主意？

编辑：

这里是我的查询结果，发现3点的JobId的之间的不同的唯一事情是如何的类别名称，这是标签。

下面列举一下我的表看起来像

-Tagmapping表：

-Tag表

- “产品表”（在这种情况下，它的我的工作表）

这里是我的存储过程：

ALTER PROCEDURE [dbo].[JobPostingSelectAll]      
(      
    @StartRowIndex  INT,      
    @PageSize   INT,      
    @OrderBy   VARCHAR(50),      
    @OrderByDirection VARCHAR(4),      
    @CurrentUserId  INT,    
    @CategoryId  INT      
)      
AS      
SET NOCOUNT ON            



SELECT   
    JobId,   
    Title,      
    Answers,   
    UserId,     
     UserName,   
     ProfileImageName,   
     CategoryId,   
     CategoryName,   
     Fees,    
     DESCRIPTION,     
     DateCreated,  
     UniqueTitle,  
     IsSecured         
FROM (      
      SELECT J.JobId,   
     J.Title,   
     (SELECT COUNT(ja2.JobId) FROM JobApplication ja2 left join Deliverable d2 ON d2.DeliverableId = ja2.DeliverableId 
     WHERE ja2.JobId=j.JobId and (d2.PurchaseCount>0 OR d2.IsFrozen=0)) AS Answers,    
        J.UserId,   
        U.UserName,   
        U.ImageName as ProfileImageName,   
        J.CategoryId,   
        C.CategoryName,   
        J.Fees,   
        J.Description,            
        J.DateCreated,  
        J.UniqueTitle,  
        J.IsSecured,             
        ROW_NUMBER() OVER(      
         ORDER BY     
         CASE      
          WHEN @OrderByDirection = 'asc' AND @OrderBy = 'Answers'    
          THEN (SELECT COUNT(ja2.JobId) FROM JobApplication ja2 left join Deliverable d2 ON d2.DeliverableId = ja2.DeliverableId 
     WHERE ja2.JobId=j.JobId and (d2.PurchaseCount>0 OR d2.IsFrozen=0)) END ASC,    
         CASE      
          WHEN @OrderByDirection = 'asc' AND @OrderBy = 'Answers'    
          THEN J.DateCreated END DESC,    
         CASE      
          WHEN @OrderByDirection = 'asc' AND @OrderBy = 'Answers'    
          THEN J.Title END ASC,    
         CASE      
          WHEN @OrderByDirection = 'desc' AND @OrderBy = 'Answers'    
          THEN (SELECT COUNT(ja2.JobId) FROM JobApplication ja2 left join Deliverable d2 ON d2.DeliverableId = ja2.DeliverableId 
     WHERE ja2.JobId=j.JobId and (d2.PurchaseCount>0 OR d2.IsFrozen=0)) END DESC,            
     CASE      
          WHEN @OrderByDirection = 'desc' AND @OrderBy = 'Answers'    
          THEN J.DateCreated END DESC,    
         CASE      
          WHEN @OrderByDirection = 'desc' AND @OrderBy = 'Answers'    
          THEN J.Title END ASC,    
         CASE WHEN @OrderByDirection = 'asc' AND @OrderBy = 'Fees'    
     THEN J.Fees END ASC,    
     CASE WHEN @OrderByDirection = 'asc' AND @OrderBy = 'Fees'    
     THEN J.DateCreated END DESC,    
     CASE WHEN @OrderByDirection = 'desc' AND @OrderBy = 'Fees'    
     THEN J.Fees END DESC,    
         CASE WHEN @OrderByDirection = 'desc' AND @OrderBy = 'Fees'    
     THEN J.DateCreated END DESC,    
         CASE WHEN @OrderByDirection = 'asc' AND @OrderBy = 'DateCreated'    
     THEN J.DateCreated END ASC,      
         CASE WHEN @OrderByDirection = 'desc' AND @OrderBy = 'DateCreated'    
     THEN J.DateCreated END DESC    
        ) AS RowIndex   
      FROM [JobPosting] J  
       LEFT JOIN TagMapping TM ON J.JobId = TM.QuestionId  
         LEFT JOIN Categories C ON TM.TagId = C.CategoryID    
      Left Join [User] U ON J.UserId = U.UserID    
      WHERE J.IsLocked = 0 AND j.IsDeleted = 0           
     AND (@CategoryId IS NULL OR J.CategoryId = @CategoryId)    

     ) AS JobPostingList      
WHERE RowIndex BETWEEN @StartRowIndex AND (@StartRowIndex + @PageSize) - 1    


SELECT COUNT(J.JobID) AS TotalRecords      
FROM JobPosting J          
WHERE J.IsLocked = 0 AND J.IsDeleted = 0       
     AND (@CategoryId IS NULL OR J.CategoryId = @CategoryId)   


-- select all filecount grouped by Type Of File for specific Job     
SELECT J.JobId, F.MimeType, COUNT(F.FileId) AS FileCount     
FROM     
JobPosting J 
Left Join Files F ON F.JobPostingId = J.JobId 
WHERE J.IsLocked = 0 AND J.IsDeleted = 0       
     AND (@CategoryId IS NULL OR J.CategoryId = @CategoryId)   
GROUP BY         
     F.MimeType,J.JobId 
Having COUNT(F.FileId) > 0 

Answer 1

问题的发生是因为你的数据库结构的标准化标签数据为每个产品（我发现this page是一个很好的参考），我可能是错的。

当你SELECT从Products表和JOIN到你的标签表，它的关键是要记住，你没有得到的产品列表;相反，你得到的产品，标签上的列表组合

如果你想获得。前10名产品列表以及他们的标签i载文信息，我建议使用子查询：

select * from 
    (select top 10 * from ProductsTable) TopProducts 
    inner join Tagmapping on TopProducts.ProductID = Tagmapping.ProductID 
    inner join Tags on Tagmapping.TagID = Tags.TagID 

即使这种解决您最初的选择问题，这仍然会产生那种多的上市告诉你以上，其中仅标签信息行与行不同。

可以将输出格式化为具有多个标记条目（可以用逗号分隔）as described here，但这将是您在将数据呈现给用户之前的最后一步（通过SQL或无论你使用什么软件层作为中介。

Answer 2

我相信，如果你不感兴趣的标签名称，您可以选择除标签名称之外的所有列，并使用“选择不同”来仅显示没有标签的产品。虽然你遇到=（