如何使用匹配的外鍵值返回唯一對象？

Question

我有一個拆分選擇語句，我在第一個目標SELECT中返回給定電子郵件的所有唯一儀表板。

然後第二個SELECT返回與唯一儀表板的ID相匹配的關聯圖表和KPI外鍵。

所以我做的嘗試是使用兩個選擇之間的UNION，這給出了一個錯誤All queries combined using a UNION, INTERSECT or EXCEPT operator must have an equal number of expressions in their target lists。

我在這裏做了come across a similar issue但在選擇之間添加偶數列值的解決方案不適合這種情況。

問：

你怎麼可以返回唯一對象匹配的外鍵值？

這是我想出了目前的程序，但我接受更好的替代品：

ALTER PROCEDURE [dbo].[GetUserProfile] 
    @p_email VARCHAR(100) 
AS 

    BEGIN  

      SELECT UserName, Email, Dashboard_Name, RID from [dbo].[User] 
       inner join [dbo].[Dashboard] on 
       [Dashboard].[USER_ID]=[User].Email 
       and Email=@p_email  
      UNION 
       SELECT KPI_Name, Chart_Name FROM [KPI] 
      inner join [dbo].[Chart] on 
       [Chart].[KPI_ID]=[KPI].ID 

    END 

而且這是四個表的要點，外鍵約束已經爲簡潔，刪除：

TABLE [dbo].[User](
[ID] [int] IDENTITY(1,1) NOT NULL, 
[UserName] [varchar](50) NOT NULL, 
[Email] [varchar](80) NOT NULL,   


TABLE [dbo].[Dashboard](
[ID] [int] IDENTITY(1,1) NOT NULL, 
[Dashboard_Name] [varchar](100) NOT NULL, 
[RID] [nvarchar](255) NOT NULL, 
[USER_ID] [varchar](80) NOT NULL 


TABLE [dbo].[KPI](
[ID] [int] IDENTITY(1,1) NOT NULL, 
[KPI_Name] [varchar](100) NOT NULL, 
[DashboardID] [int] NOT NULL, 


TABLE [dbo].[Chart](
[ID] [int] IDENTITY(1,1) NOT NULL, 
[Chart_Name] [varchar](100) NOT NULL, 
[KPI_ID] [int] NOT NULL, 

所以這將是預期的結果，如果查詢是正確的：

{ 
    UserName:"brian", 
    Email:"brian@gmail.com", 
    Dashboard_Name:"test dash 1", 
    RID:"2003", 
    DashboardID:1, 
    KPI_Name:"test kpi 1", 
    KPI_ID:1, 
    Chart_ID:1, 
    Chart_Name:"ch1, ch2, ch3" 
}, 
{ 
    UserName:"brian", 
    Email:"brian@gmail.com", 
    Dashboard_Name:"test dash 2", 
    RID:"2003", 
    DashboardID:2, 
    KPI_Name:"test kpi 2", 
    KPI_ID:2, 
    Chart_ID:2, 
    Chart_Name:"ch4, ch5, ch6" 
}, 

Answer 1

你的聯盟將無法正常工作。嘗試這個。

SELECT UserName, Email, Dashboard_Name, RID, Dashboard.ID as Dashboard_ID, KPI_Name, KPI.ID as KPI_ID,Chart.ID as Chart_ID, Chart_Name 
    from [User] 
    inner join [Dashboard] on [Dashboard].[USER_ID]=[User].Email 
       and [User].Email=@p_email 
    Inner Join [KPI] ON [Dashboard].[Dashboard_ID] = [KPI].[Dashboard_ID] 
    Inner Join [Chart] ON [KPI].[ID] = [Chart].[KPI_ID] 

Answer 2

這個幫助;我已經習慣了與Oracle語法，所以我不知道，如果你需要更多或更少的分支：如上所述

ALTER PROCEDURE [dbo].[GetUserProfile] 
    @p_email VARCHAR(100) 
AS 
BEGIN 
DECLARE 
    vUserName [varchar](50); 
    vEmail [varchar](80); 
    vDashboard_Name [varchar](100); 
    vRID [nvarchar](255); 
    vDashboardId [int]; 
    vKPI_Name [varchar](100); 
    vChart_Name [varchar](100); 
BEGIN 
    SELECT U.UserName, U.Email, D.Dashboard_Name, 
     D.RID, D.ID 
    INTO vUserName, vEmail, vDashboard_Name, 
     vRID, vDashboardId 
    FROM [dbo].[User] U INNER JOIN [dbo].[Dashboard] D ON D.[USER_ID]=U.Email 
    WHERE U.Email=@p_email;  

    SELECT K.KPI_Name, C.Chart_Name 
    INTO vKPI_Name, vChart_Name 
    FROM [KPI] K INNER JOIN [dbo].[Chart] C ON C.[KPI_ID]=K.ID 
    WHERE K.DashboardID = vDashboardId; 
END; 
END;