左外连接没有给出任何结果

Posted 2023-03-28

【中文标题】左外连接没有给出任何结果

【英文标题】：Left Outer Join is not giving any result

【发布时间】：2016-02-11 09:12:12

【问题描述】：

我想加入包含 Portal_Order 表中的所有值以及其他表中的其他匹配值的表。 左外连接不返回值

查询：

With Max_Date As (Select Max(Change_Date) Change_Date, Ocoe_Job_Id 
From Ocoe_Job_Status Where Ocoe_Job_Id In 
(Select Ocoe_Job_Id From Portal_Order Where To_Char(Created_Date,'YYYY-MM-DD') 
Between ( Select To_Char(Sysdate-1000,'YYYY-MM-DD') From Dual) 
And ( Select To_Char(Sysdate,'YYYY-MM-DD') From Dual)  ) 
Group By Ocoe_Job_Id) 

Select Order_Id, Order_Name, Order_Desc, B.Description As Order_Status, C.Ocoe_Job_Id, C.Comments 
As Communication_Id , Communication_Name, Created_By, Count(*) Over () As Total_Record_Count, Row_Number()
Over ( Order By Order_Id ) Row_Number 
From  Max_Date D,
Ocoeowner.Portal_Order A
Left Outer Join Ocoeowner.Ocoe_Job_Status C On C.Ocoe_Job_Id =A.Ocoe_Job_Id
LEFT OUTER JOIN Ocoeowner.Portal_Order_Status_Code_Lk B on A.Order_Status = B.Status_Code
 Where To_Char(Created_Date,'YYYY-MM-DD') 
Between ( Select To_Char(Sysdate-1000,'YYYY-MM-DD') From Dual) And ( Select To_Char(Sysdate,'YYYY-MM-DD') From Dual)  
And C.Ocoe_Job_Id = D.Ocoe_Job_Id And D.Change_Date = C.Change_Date AND communication_name='ptuletters';

【问题讨论】：

当您使用双表（和 plsql）时，表明您使用的是 Oracle 而不是 mysql

MySQL 也不支持with name as ...，所以它似乎是一个不正确的标签

【参考方案1】：

谓词条件需要在连接的On 子句中，而不是在where 子句中。外部联接的工作方式是在分析联接条件之后，将所有与内部不匹配的“外部”行添加回......但这一切都发生在处理 where 子句之前。因此，如果 where 子句谓词从外连接的外侧过滤属性，则所有这些行将再次被删除......（它们都是空的）。将谓词放在连接条件中

And C.Ocoe_Job_Id = D.Ocoe_Job_Id And D.Change_Date = C.Change_Date 

必须移动，也可能是AND communication_name='ptuletters'，取决于源表

【参考方案2】：

试试这个：

WITH Max_Date AS
  (SELECT MAX(Change_Date) Change_Date,
    Ocoe_Job_Id
  FROM Ocoe_Job_Status
  WHERE Ocoe_Job_Id IN
    (SELECT Ocoe_Job_Id
    FROM Portal_Order
    WHERE TO_CHAR(Created_Date,'YYYY-MM-DD') BETWEEN
      ( SELECT TO_CHAR(Sysdate-1000,'YYYY-MM-DD') FROM Dual
      )
    AND ( SELECT TO_CHAR(Sysdate,'YYYY-MM-DD') FROM Dual)
    )
  GROUP BY Ocoe_Job_Id
  )

SELECT Order_Id,
  Order_Name,
  Order_Desc,
  B.Description AS Order_Status,
  C.Ocoe_Job_Id,
  C.Comments AS Communication_Id ,
  Communication_Name,
  Created_By,
  COUNT(*) Over () AS Total_Record_Count,
  Row_Number() Over ( Order By Order_Id ) Row_Number
FROM 
 Ocoeowner.Portal_Order A LEFT OUTER JOIN Ocoeowner.Ocoe_Job_Status C ON
  A.Ocoe_Job_Id=C.Ocoe_Job_Id
 LEFT OUTER JOIN Ocoeowner.Portal_Order_Status_Code_Lk B ON
  A.Order_Status = B.Status_Code
 LEFT OUTER JOIN Max_Date D ON
  C.Ocoe_Job_Id     = D.Ocoe_Job_Id
  AND C.Change_Date     = D.Change_Date
WHERE 
 TO_CHAR(Created_Date,'YYYY-MM-DD') BETWEEN
  ( SELECT TO_CHAR(Sysdate-1000,'YYYY-MM-DD') FROM Dual
  )
 AND ( SELECT TO_CHAR(Sysdate,'YYYY-MM-DD') FROM Dual)
AND NVL(communication_name, 'ptuletters')='ptuletters';