Question

我的问题是，只有当MainRule表具有与Table1表匹配的ID时，此查询才有效。即使MainRule表没有匹配的ID，我也需要查询才能工作。即使在MainRule表中没有匹配的记录，表1中的记录也应该显示。

这是我的代码：

SELECT  Person, OrderNum, Name, County, SubmitDate, Days1, 
        SUM(Date_Diff) - 1 AS [Number of Uncleared Days] 
  From
     (SELECT D1.RecordID AS Person, D3.[case no] AS OrderNum, 
             D3.FullName AS Name, D3.County, D3.[SignedDate] AS SubmitDate,
                  DATEDIFF(d, D3.[SignedDate], D3.closedate) AS Days1,
                  DATEDIFF(DAY, [HoldDate],
                  (SELECT TOP 1 [StatusDate]
                     FROM [MainRule] D2
                    WHERE D2.Status = 'Cleared' 
                      AND D1.RecordID = D2.RecordID 
                      AND D1.StatusDate < D2.StatusDate)) AS [Date_Diff]
        FROM [MainRule] AS D1 INNER JOIN table1 AS D3 ON D3.ID = D1.RecordID
       WHERE D1.Status = 'UnCleared') SubQ 
WHERE (SubmitDate BETWEEN '10/01/2017' and '10/17/2017')
GROUP BY Person, OrderNum, Name, County, SubmitDate, Days1

Answer 1

只需使用LEFT JOIN：

SELECT  Person, OrderNum, Name, County, SubmitDate, Days1, 
        SUM(Date_Diff) - 1 AS [Number of Uncleared Days] 
  From
     (SELECT D1.RecordID AS Person, D3.[case no] AS OrderNum, 
             D3.FullName AS Name, D3.County, D3.[SignedDate] AS SubmitDate, 
                  DATEDIFF(d, D3.[SignedDate], D3.closedate) AS Days1, 
                  DATEDIFF(DAY, [HoldDate],                                                      
                  (SELECT TOP 1 [StatusDate]
                     FROM [MainRule] D2
                    WHERE D2.Status = 'Cleared' 
                      AND D1.RecordID = D2.RecordID 
                      AND D1.StatusDate < D2.StatusDate)) AS [Date_Diff]
        FROM table1 AS D3
        LEFT JOIN [MainRule] AS D1 ON D3.ID = D1.RecordID
       WHERE D1.Status = 'UnCleared')  SubQ 
WHERE (SubmitDate BETWEEN '10/01/2017' and '10/17/2017')
GROUP BY Person, OrderNum, Name, County, SubmitDate, Days1

这样，即使另一个表MainRule中没有匹配的行，您也会从table1（左表）中获取所有行。

您应该阅读有关联接类型之间差异的更多信息：

A Visual Explanation of SQL Joins

Answer 2

您有两个问题：INNER JOIN（正如其他答案所解释的）和WHERE D1.Status = 'UnCleared'。

无论您的联接是什么，WHERE子句将排除没有匹配的MainRule行的行。

尝试类似WHERE D1.Status = 'UnCleared' OR D1.Status IS NULL的内容。

除非两个表之间存在匹配，否则我的数据不会显示

2 个答案: