Question

我正在尝试累积SQL Server送货系统中事件事件总数的年初至今，以便在图表中显示。

我现在所拥有的：

SELECT EventType.Name AS [Incident Name], COUNT(Event.ID) AS [Occurrence]
FROM  Event
INNER JOIN
        PortEvent ON Event.PortEventID = PortEvent.ID
INNER JOIN
        EventType ON PortEvent.EventID = Event.ID

WHERE Event.IsIncident = 1 and Event.Date BETWEEN (Start of Year & Now)
GROUP BY Event.Name

这会返回什么;

Incident Name       Occurrence

Incident 1              1
Incident 3              4
Incident 4              7

我想要的是什么：

Incident Name       Occurrence

Incident 1              1
Incident 2              0
Incident 3              4
Incident 4              7
Incident 5              0

有没有办法简单地做到这一点？我在SO上看到了一些例子，但仅用于相邻的表格。

由于

Answer 1

您的EventType ON PortEvent.EventID = Event.ID条件存在问题。以下查询必须解决您的问题。

SELECT ET.Name AS [Incident Name], COUNT(E.ID) AS [Occurrence]
FROM EventType ET
  LEFT JOIN PortEvent PE
    ON ET.ID = PE.EventID
  LEFT JOIN Event E
    ON PE.EventID = E.ID
      AND E.IsIncident = 1
      AND E.Date BETWEEN ([Start of Year] AND Now)
GROUP BY ET.Name

<强>更新

如果您只想包含在结果事件中，可以尝试这样做：

    ON PE.EventID = E.ID
      AND E.Date BETWEEN ([Start of Year] AND Now)
   WHERE E.IsIncident = 1
GROUP BY ET.Name

Answer 2

仅使用左连接是不够的。您需要重新排序查询，以便所有事件类型都位于最左侧的记录集中（无论如何我都是可视化的）。此外，您需要删除where子句并将其添加到事件表的连接中，因为如果不是，它也可能是内连接。

SELECT
    EventType.Name AS [Incident Name], COUNT(Event.ID) AS [Occurrence]
FROM  EventType
LEFT JOIN PortEvent ON Event.PortEventID = PortEvent.ID
LEFT JOIN Event ON PortEvent.EventID = Event.ID and Event.IsIncident = 1 and Event.Date BETWEEN (Start of Year & Now)
GROUP BY Event.Name

Answer 3

（CASE WHEN COUNT（Event.ID）= 0那么0 ELSE COUNT（Event.ID）END）AS [Occurrence]

Answer 4

将EventType的INNER JOIN更改为Left Join。这将返回Event和零个或多个EventType

SELECT EventType.Name AS [Incident Name], COUNT(Event.ID) AS [Occurrence] 
FROM  Event
LEFT JOIN
        PortEvent ON Event.PortEventID = PortEvent.ID
LEFT JOIN
        EventType ON PortEvent.EventID = Event.ID

WHERE Event.IsIncident = 1 and Event.Date BETWEEN (Start of Year & Now)
GROUP BY Event.Name

显示具有0计数的行

4 个答案: