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我正在使用历史学家来搜索特定标签的某些值。历史学家有一定的规则，例如，我不能创建或删除表，查询需要标记名等。

例如，我想搜索 TagName 'Tank1' 并返回其 DateTime 和 Value 结果，然后使用这些结果进一步搜索标签以匹配在该 DateTime 具有相同值的那些标签。

我在给定日期和时间之间搜索“Tank1”并收到 4 个结果，如下所示
2021-11-02 08:00:54.9870000 1
2021-11-02 10:22:27.9850000 1
2021-11-02 11:47:31.3360000 2
2021-11-02 23:11:57.8120000 2

因此，我需要搜索其他四个标签并返回与 dateTime 和 value 匹配的结果。

下面的代码是我制作的（我现在应该告诉你我是一个虚拟新手）

DECLARE @AT1Value INT,
        @AT1DateTime DateTime
SELECT  @AT1Value = Value,                              --GETS THE VALUES OF AT1 STERILISER
        @AT1DateTime = DateTime                         --GETS THE DATETIME OF AT1 STERILISER VALUES
From Runtime.dbo.v_History
Where 
    Runtime.dbo.v_History.Tagname = 'AT1_Select_ster'
AND Runtime.dbo.v_History.DateTime >= '2021-11-02 08:00'
AND Runtime.dbo.v_History.DateTime <= '2021-11-03 08:01'
AND Runtime.dbo.v_History.Value > 0


Select  a.DateTime,
        a.TagName,
        a.Value
From Runtime.dbo.v_History AS a        --GETS  THE VALUES OF THE FM TAGS AT THE DATETIME OF AT1 STERILISER VALUES
Where  
    ((a.TagName = 'FM_S1_Batch' AND a.Value = @AT1Value AND a.DateTime = @AT1DateTime)
OR  (a.Tagname = 'FM_S2_batch' AND a.Value = @AT1Value AND a.DateTime = @AT1DateTime)
OR  (a.Tagname = 'FM_S3_batch' AND a.Value = @AT1Value AND a.DateTime = @AT1DateTime)
OR  (a.Tagname = 'FM_S4_batch' AND a.Value = @AT1Value AND a.DateTime = @AT1DateTime))
AND a.Value > 0

这很好用，尽管它只产生下面的最后一个 dateTime 和 Value 结果，
2021-11-02 23:11:57.8120000 FM_S2_batch 2

我是否正确地假设这是因为变量每次都被覆盖并且只保存最后一个值？

应该返回的结果应该类似于下面的结果
2021-11-02 08:00:54.9870000 FM_S1_batch 1
2021-11-02 10:22:27.9850000 FM_S1_batch 1
2021-11-02 11:47:31.3360000 FM_S2_batch 2
2021-11-02 23:11:57.8120000 FM_S2_batch 2

无论如何我可以进行多次扫描并保存每个结果，直到获得所需的所有结果？还是有更简单更合适的方法（我猜有）。

TIA

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2 回答 2

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感谢所有花时间回复我的问题的人。感谢@EdmCoff 建议尝试使用for循环或游标，我终于可以使用游标工作了。

for 循环返回最后一个值 4 次，所以我尝试了游标，它对我有用。

我在下面发布了适合我的代码

DECLARE @AT1Value INT,
        @AT1DateTime DateTime
        
DECLARE cursor_result CURSOR                                

FOR SELECT  Runtime.dbo.v_History.Value,                    
        Runtime.dbo.v_History.DateTime                      
From Runtime.dbo.v_History
Where 
    Runtime.dbo.v_History.Tagname = 'AT1_Select_ster'
AND Runtime.dbo.v_History.DateTime >= '2021-11-02 08:00'
AND Runtime.dbo.v_History.DateTime <= '2021-11-04 08:01'
AND Runtime.dbo.v_History.Value > 0

OPEN cursor_result                                          
FETCH NEXT FROM cursor_result INTO                          
    @AT1Value,
    @AT1DateTime

WHILE @@FETCH_STATUS = 0                                    
Select  a.DateTime,
        a.TagName,
        a.Value
From Runtime.dbo.v_History AS a                             
Where  
    ((a.TagName = 'FM_S1_Batch' AND a.Value = @AT1Value AND a.DateTime = @AT1DateTime)
OR  (a.Tagname = 'FM_S2_batch' AND a.Value = @AT1Value AND a.DateTime = @AT1DateTime)
OR  (a.Tagname = 'FM_S3_batch' AND a.Value = @AT1Value AND a.DateTime = @AT1DateTime)
OR  (a.Tagname = 'FM_S4_batch' AND a.Value = @AT1Value AND a.DateTime = @AT1DateTime))
AND a.Value > 0
FETCH NEXT FROM cursor_result INTO                                      
@AT1Value,
@AT1DateTime
END
CLOSE cursor_result                                         
DEALLOCATE cursor_result
于 2021-12-13T12:56:48.750 回答
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如果我理解正确，您希望您的int和datetime变量（@AT1DateTime 和@AT1Value）将包含第一个查询返回的多个值。那是行不通的（正如您所指出的，它们将只保留一个值）。

从提供的代码来看，您根本不清楚是否需要将这些值存储在变量中。我想你可能正在寻找类似的东西：

Select  a.DateTime,
        a.TagName,
        a.Value
From Runtime.dbo.v_History AS a        
Where  
a.TagName IN ('FM_S1_Batch', 'FM_S2_batch', 'FM_S3_batch', 'FM_S4_batch')
AND EXISTS
 (SELECT  *
 From Runtime.dbo.v_History b
 Where 
  b.Tagname = 'AT1_Select_ster'
  AND b.DateTime >= '2021-11-02 08:00'
  AND b.DateTime <= '2021-11-03 08:01'
  AND b.Value > 0
  AND b.Value = a.Value
  AND b.DateTime = a.DateTime
 )
AND a.Value > 0

这是您的两个查询合并为一个。外部查询的第二个/中间WHERE条件检查 a.value/a.datetime 组合是否存在于内部查询中。

于 2021-12-10T16:49:33.417 回答