返回重复行

Question

我正在执行下面的查询，但当我们没有“LastMonth”和“CurrentMonth”的任何记录时，会返回重复的行。请告诉我问题出在哪里？

**Output:**
Project ProCount CurrentDateAvg thisWeekAvg thisMonthAvg lastMonthAvg           
xyz         0            0          0.19       0.09       0
xyz         5            0          0.0         0.0       0


WITH 
ThisWeek AS (SELECT  'xyz' as 'Project_Name', 0.19 as 'thisWeekAvg' ), 
ThisMonth AS ( SELECT  'xyz' as 'Project_Name', 0.09 as 'thisMonthAvg'), 
LastMonth AS( SELECT  'xyz' as 'Project_Name', 0 as 'lastMonthAvg'  where 1=2), 
CurrentDate AS( SELECT  'xyz' as 'Project_Name', 0 as 'CurrentDateAvg'  where 1=2), 
ProjectCount AS( SELECT  'xyz' as 'Project_Name', 5 AS 'ProCount' ) 
              SELECT 
                             COALESCE(w.Project_Name, m.Project_Name, l.Project_Name,c.Project_Name,pc.Project_Name) AS 'Project',
                             COALESCE(pc.ProCount,0) 'ProCount', 
                             COALESCE(c.CurrentDateAvg,0) 'CurrentDateAvg', 
                             COALESCE(w.thisWeekAvg,0) 'thisWeekAvg', 
                             COALESCE(m.thisMonthAvg,0) 'thisMonthAvg', 
                             COALESCE(l.lastMonthAvg,0) 'lastMonthAvg' 
                             FROM 
                             ThisWeek w 
                             FULL OUTER JOIN ThisMonth m ON         w.Project_Name = m.Project_Name
                             FULL OUTER JOIN LastMonth l    ON         m.Project_Name = l.Project_Name
                             FULL OUTER JOIN ProjectCount pc ON    l.Project_Name = pc.Project_Name 
                             FULL OUTER JOIN CurrentDate c ON         pc.Project_Name = c.Project_Name

Answer 1

这是预期的行为，因为您没有在

NULL

中处理

JOIN

值。

为了方便起见，让我们给它们编号：

ThisWeek w --1
FULL OUTER JOIN ThisMonth m ON w.Project_Name = m.Project_Name --2
FULL OUTER JOIN LastMonth l ON m.Project_Name = l.Project_Name --3
FULL OUTER JOIN ProjectCount pc ON l.Project_Name = pc.Project_Name --4
FULL OUTER JOIN CurrentDate c ON pc.Project_Name = c.Project_Name --5

所以我们有：

1. 本周有一个名为“xyz”的项目。
2. 本月，有一个“xyz”项目加入本周（也有“xyz”）
3. 上个月，没有项目，到

   JOIN

   到本月（无行

   JOIN

   ed）
4. 当前数据，无项目，至 J

   OIN

   至上个月（无行

   JOIN

   ed）
5. 项目计数，项目为“xyz”，到

   JOIN

   没有行；由于

   FULL OUTER JOIN

   创建一个新行。

   NULL <> 'xyz'

对于这样的东西，您可能需要一个

IN

：

WITH
    ThisWeek AS (
        SELECT
            'xyz' AS Project_Name,
            0.19 AS thisWeekAvg
    ),
    ThisMonth AS (
        SELECT
            'xyz' AS Project_Name,
            0.09 AS thisMonthAvg
    ),
    LastMonth AS (
        SELECT
            'xyz' AS Project_Name,
            0 AS lastMonthAvg
        WHERE
            1 = 2
    ),
    CurrentDate AS (
        SELECT
            'xyz' AS Project_Name,
            0 AS CurrentDateAvg
        WHERE
            1 = 2
    ),
    ProjectCount AS (
        SELECT
            'xyz' AS Project_Name,
            5 AS ProCount
    )
SELECT
    COALESCE(
        w.Project_Name,
        m.Project_Name,
        l.Project_Name,
        c.Project_Name,
        pc.Project_Name
    ) AS Project,
    COALESCE(pc.ProCount, 0) ProCount,
    COALESCE(c.CurrentDateAvg, 0) CurrentDateAvg,
    COALESCE(w.thisWeekAvg, 0) thisWeekAvg,
    COALESCE(m.thisMonthAvg, 0) thisMonthAvg,
    COALESCE(l.lastMonthAvg, 0) lastMonthAvg
FROM
    ThisWeek w
    FULL OUTER JOIN ThisMonth m ON w.Project_Name = m.Project_Name --WE don't need an IN here
    FULL OUTER JOIN LastMonth l ON l.Project_Name IN (w.Project_Name,m.Project_Name)
    FULL OUTER JOIN ProjectCount pc ON pc.Project_Name IN (w.Project_Name,m.Project_Name,l.Project_Name)
    FULL OUTER JOIN CurrentDate c ON c.Project_Name IN (w.Project_Name,m.Project_Name,l.Project_Name,pc.Project_Name);