將SQL查詢合併爲相似的結果

Question

我現在有一個系統存儲與每個產品關聯的產品和標籤。

例

產品：話筒

標籤：音樂，電子，音響

有一個標籤表，產品列表，並TagProductMapping表。第三張表格顯然將產品映射到標籤以獲得一對多的關係。當我使用LEFT JOIN查詢Microphone產品時，我得到3條記錄幾乎是重複的，除了「TagName」列之外，顯然它有3個不同的標籤。我怎樣才能合併這個結果？它令人沮喪，因爲如果我試圖精確地查詢10個產品，它將僅限於10個結果，這不會是10個產品。

任何人都有這個好主意？

編輯：

這裏是我的查詢結果，發現3點的JobId的之間的不同的唯一事情是如何的類別名稱，這是標籤。

下面列舉一下我的表看起來像

-Tagmapping表：

-Tag表

- 「產品表」（在這種情況下，它的我的工作表）

這裏是我的存儲過程：

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

問題的發生是因爲你的數據庫結構的標準化標籤數據爲每個產品（我發現this page是一個很好的參考），我可能是錯的。

當你SELECT從Products表和JOIN到你的標籤表，它的關鍵是要記住，你沒有得到的產品列表;相反，你得到的產品，標籤上的列表組合

如果你想獲得。前10名產品列表以及他們的標籤i載文信息，我建議使用子查詢：

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

即使這種解決您最初的選擇問題，這仍然會產生那種多的上市告訴你以上，其中僅標籤信息行與行不同。

可以將輸出格式化爲具有多個標記條目（可以用逗號分隔）as described here，但這將是您在將數據呈現給用戶之前的最後一步（通過SQL或無論你使用什麼軟件層作爲中介。

Answer 2

我相信，如果你不感興趣的標籤名稱，您可以選擇除標籤名稱之外的所有列，並使用「選擇不同」來僅顯示沒有標籤的產品。雖然你遇到=（