Sql 引用子选择之外的别名

下面描述了我想对该表执行的操作 左边是一个表格，我想计算每个事件的“当前值” 代码1将当前_值重置为默认值 代码2将值添加到当前值 代码3使用值减少当前的_值

Table Events                        |column to be calculated                                
eventId  deviceId EventCode value   |current_value                              
1          1        1          2    |2                          
2          1        2          1    |3                          
3          1        2          1    |4                          
4          1        2          1    |5                              
5          1        3          2    |3                              
6          1        2          2    |5                              
7          1        1          1    |1                              
8          1        2          2    |3          code 1: set                     
9          1        2          1    |4          code 2: add                     
10         1        2          1    |5          code 3: subtract                        
11         1        3          3    |2                              

我的SQL代码看起来像

Select                                                  
    EventId,                                                
    deviceId,                                               
    (select last(value) from Events as E where E.EventCode = 1 and E.DeviceID = DeviceID and E.EventId<EventId) AS LastSetValue,                                                
    (select last(value) from Events as E where E.EventCode = 1 and E.DeviceID = DeviceID and E.EventId<EventId) AS FromEventID,                                             
    (select sum(value) from Events as E where E.EventCode = 2 and E.DeviceID = DeviceID and E.EventId between fromEventId and EventId) AS SumOfAdded,                                               
    (select sum(value) from Events as E where E.EventCode = 3 and E.DeviceID = DeviceID and E.EventId betweein FromEventId and EventId) AS SumOfSubtracted,                                             
    LastSetValue+SumOfAdded-SumofSubtracted as current_value                                                
from Events;

这段代码似乎不起作用，因为在子选择部分DeviceID看起来是内部临时表DeviceID，当我别名外部DeviceID时，这也将不起作用，因为找不到它。From EventID也有这个问题

---

如果您能帮我解决问题，我们将不胜感激。

我不确定我是否100%理解您的问题，但如果我读的内容正确，您只需将外部表格别名如下：

Select                                                  
    t.EventId,                                                
    t.DeviceId,                                               
    (select last(value) from Events as E where E.EventCode = 1 and E.DeviceID = t.DeviceID and E.EventId<t.EventId) AS LastSetValue,                                                
    (select last(value) from Events as E where E.EventCode = 1 and E.DeviceID = t.DeviceID and E.EventId<t.EventId) AS FromEventID,                                             
    (select sum(value) from Events as E where E.EventCode = 2 and E.DeviceID = t.DeviceID and E.EventId between fromEventId and t.EventId) AS SumOfAdded,                                               
    (select sum(value) from Events as E where E.EventCode = 3 and E.DeviceID = t.DeviceID and E.EventId between FromEventId and t.EventId) AS SumOfSubtracted,                                             
    LastSetValue+SumOfAdded-SumofSubtracted as current_value                                                
from Events t;

---

你能不用代码描述当前值代表什么吗？当前值是设备在被测量时的长度。eventID链接到日期或时间。它是初始值加上附加长度的集合，有时从设备中减少零件。有时整个设备被替换为一个新的设备，重新开始使用一个新的初始值；我应该把别名放在哪里？@hbl-就在事件和内部连接之间，就像事件t内部连接。。。