SQL 联合/加入/相交多个 select 语句

Question

我有两个 select 语句。一个人获得过去 60 秒内记录的电压数据列表（如果有）和相关腔室名称，一个人获得过去 5 分钟内记录的电弧事件数据列表（如果有）。我正在尝试将电弧计数数据作为新列附加到电压数据 table。我不知道该怎么做。

请注意，对于电压数据 table 中的给定腔室名称，可能有也可能没有电弧计数行。如果没有行，我想将弧计数列值设置为零。

关于如何实现这个的任何想法？

电压数据：

SELECT DISTINCT dbo.CoatingChambers.Name, 
AVG(dbo.CoatingGridVoltage_Data.ChanA_DCVolts) AS ChanADC,             
AVG(dbo.CoatingGridVoltage_Data.ChanB_DCVolts) AS ChanBDC, 
AVG(dbo.CoatingGridVoltage_Data.ChanA_RFVolts) AS ChanARF, 
AVG(dbo.CoatingGridVoltage_Data.ChanB_RFVolts) AS ChanBRF FROM 
dbo.CoatingGridVoltage_Data LEFT OUTER JOIN dbo.CoatingChambers ON 
dbo.CoatingGridVoltage_Data.CoatingChambersID = 
dbo.CoatingChambers.CoatingChambersID WHERE 
(dbo.CoatingGridVoltage_Data.DT > DATEADD(second, - 60, 
SYSUTCDATETIME())) GROUP BY dbo.CoatingChambers.Name

Returns

Name |      ChanADC      |       ChanBDC      |       ChanARF       |     ChanBRF
-----+-------------------+--------------------+---------------------+------------------
OX2  | 2.9099999666214   | -0.485000004371007 | 0.344801843166351   | 0.49748428662618
S2   | 0.100000001490116 | -0.800000016887983 | 0.00690172302226226 | 0.700591623783112
S3   | 4.25666658083598  |  0.5               | 0.96554297208786    | 0.134956782062848

弧数table:

SELECT CoatingChambers.Name,
SUM(ArcCount) as ArcCount
FROM CoatingChambers
LEFT JOIN CoatingArc_Data
ON dbo.[CoatingArc_Data].CoatingChambersID = dbo.CoatingChambers.CoatingChambersID 
where EventDT > DATEADD(mi,-5, GETDATE())
Group by Name

Returns

Name | ArcCount
-----+---------
L1   |   283
L4   |     0
L6   |     1
S2   |    55

为了清楚起见，我想要这个 table（添加了弧计数列），鉴于上面的两个 table：

Name |      ChanADC      |       ChanBDC      |       ChanARF       | ChanBRF           | ArcCount
-----+-------------------+--------------------+---------------------+-------------------+---------
OX2  | 2.9099999666214   | -0.485000004371007 | 0.344801843166351   | 0.49748428662618  |  0
S2   | 0.100000001490116 | -0.800000016887983 | 0.00690172302226226 | 0.700591623783112 | 55
S3   | 4.25666658083598  |  0.5               | 0.96554297208786    | 0.134956782062848 |  0

Answer 1

您可以将 select 语句视为虚拟表并将它们连接在一起：

select 
  x.Name,
  x.ChanADC, 
  x.ChanBDC,  
  x.ChanARF,
  x.ChanBRF,
  isnull( y.ArcCount, 0 ) ArcCount
from
(
  select distinct 
    cc.Name, 
    AVG(cgv.ChanA_DCVolts) AS ChanADC,     
    AVG(cgv.ChanB_DCVolts) AS ChanBDC,
    AVG(cgv.ChanA_RFVolts) AS ChanARF, 
    AVG(cgv.ChanB_RFVolts) AS ChanBRF 
  from
    dbo.CoatingGridVoltage_Data cgv 
      left outer join   
    dbo.CoatingChambers cc 
      on 
        cgv.CoatingChambersID = cc.CoatingChambersID 
  where 
    cgv.DT > dateadd(second, - 60, sysutcdatetime())
  group by 
    cc.Name
) as x

  left outer join

(
  select 
    cc.Name,
    sum(ac.ArcCount) as ArcCount
  from 
    dbo.CoatingChambers cc 
      left outer join 
    dbo.CoatingArc_Data ac 
      on 
        ac.CoatingChambersID = cc.CoatingChambersID 
  where 
    EventDT > dateadd(mi,-5, getdate())
  group by 
    Name    
) as y

  on 
    x.Name = y.Name

另外，用别名简化您的名字并格式化查询以提高可读性是值得的……我无耻地试了一下。

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