检索子查询的多个总和列答案

【问题标题】：Retrieve multiple sum columns of sub queries检索子查询的多个总和列
【发布时间】：2017-01-19 16:21:05
【问题描述】：

从这个查询：

    select LastStateS='LastStateS1and2'
      , count(s.LastState) as sumS,
    LasteStateE='LastStateE1and2'
      , count(e.LastState) as sumE
from table1 t1
    join table2 t2
        on t1.ID = t2.ID
    join (select LastState
                ,count(LastState) as sum
          from table1
          where ID = X
            and LastState = 1
             or LastState = 2
          group by LastState
         ) s

        on s.LastState = t1.LastState
    join (select LastState
                ,count(LastState) as sum
          from table1
          where ID = X
            and LastState = 3
             or LastState = 4
          group by LastState
         ) e

        on e.LastState = t1.LastState

我无法检索我的“laststate”条件的总和。结果我的两列都是空的。提前致谢。

【问题讨论】：

您是如何尝试检索总和列的？
table2的意义是什么？此查询中未使用它。你为什么需要它？此外，您应该在 Where 子句中的 OR 语句周围加上 ()。

标签： sql sql-server reporting-services

【解决方案1】：

我不确定您为什么在此查询中做一些未使用的事情，例如您的子查询中的count(LastState)。

我认为这就是您所需要的结果：

select 
      LastStateS ='1 and 2'
    , countS = sum(case when t1.LastState in (1,2) then 1 else 0 end)
    , LasteStateE ='3 and 4'
    , countE = sum(case when t1.LastState in (3,4) then 1 else 0 end)
  from table1 t1
    inner join table2 t2 on t1.id = t2.id and t1.id = X

要让您的原始查询返回您想要的结果，您需要对子查询使用左连接：

select 
    LastStateS='LastStateS1and2'
  , count(s.LastState) as sumS
  , LasteStateE='LastStateE1and2'
  , count(e.LastState) as sumE
from table1 t1
  inner join table2 t2 on t1.ID = t2.ID
  left join (
    select 
        LastState
      , count(LastState) as sum
      from table1
      where ID = X
        and LastState = 1
         or LastState = 2
      group by LastState
     ) s
    on s.LastState = t1.LastState
  left join (
    select 
        LastState
      , count(LastState) as sum
      from table1
      where ID = X
        and LastState = 3
         or LastState = 4
      group by LastState
     ) e
    on e.LastState = t1.LastState

另请注意，正如 @WEI_DBA 在他们的评论中指出的那样，使用 where ID = X and LastState = 3 or LastState = 4 可能会产生意想不到的后果而不是where ID = X and (LastState = 3 or LastState = 4)。

【讨论】：