如何使用匹配的外键值返回唯一对象？

Question

我有一个拆分选择语句，我在第一个目标SELECT中返回给定电子邮件的所有唯一仪表板。

然后第二个SELECT返回与唯一仪表板的ID相匹配的关联图表和KPI外键。

所以我做的尝试是使用两个选择之间的UNION，这给出了一个错误All queries combined using a UNION, INTERSECT or EXCEPT operator must have an equal number of expressions in their target lists。

我在这里做了come across a similar issue但在选择之间添加偶数列值的解决方案不适合这种情况。

问：

你怎么可以返回唯一对象匹配的外键值？

这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 

而且这是四个表的要点，外键约束已经为简洁，删除：

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, 

所以这将是预期的结果，如果查询是正确的：

{ 
    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

你的联盟将无法正常工作。尝试这个。

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

这个帮助;我已经习惯了与Oracle语法，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;