SQL Server根据参数删除不在源代码中的行

Question

我有一张需要根据天气预报进行每小时更新的表。创建表和合并的效果很好，现在我一直在使用它们。

CREATE TABLE #WeatherHourly([Pk_Id][int], 
          [ObservationDateTime] [datetime],  
          [EffectiveDateTime] [datetime], 
          [Value] [decimal](18, 4) 
          ) 

MERGE INTO WeatherHourly AS TARGET 
USING #WeatherHourly AS Source ON Target.Pk_Id = Source.Pk_Id 
           AND Target.EffectiveDateTime = Source.EffectiveDateTime 
WHEN MATCHED THEN 
    UPDATE SET Target.Value = Source.Value, 
       Target.ObservationDateTime = Source.ObservationDateTime 
WHEN NOT MATCHED BY TARGET THEN 
    INSERT ([Pk_Id], [ObservationDateTime], [EffectiveDateTime], [Value]) 
    VALUES (Source.Pk_Id, Source.ObservationDateTime, Source.EffectiveDateTime, Source.Value); 

但我注意到有时候新的预测不包括我已经写到表格中的旧数据。这意味着一些数据会被粘贴，因为在合并语句中没有写入/更新它。这个数据实际上是无效的，因为它没有包含在最新的预测中。现在只需在合并中添加“不匹配的源代码”即可，但它会删除历史记录的所有行。由于其他原因，我保留了历史记录，无法删除旧行，但只能删除WeatherHourly表中仍然相关的行（（从昨天到任何未来日期范围内的EffectiveDateTime）。下面的代码是我到目前为止所尝试的，但它会删除所有不想删除的历史记录行。

Delete from WeatherHourly from WeatherHourly tRow 
left JOIN #WeatherHourly t2 ON tRow.EffectiveDateTime = t2.EffectiveDateTime and tRow.Pk_Id = t2.Pk_Id 
where t2.PK_Id is null 

任何帮助，将不胜感激。

编辑为我的新方法： 我想知道如何使用更好的选择为我的原始合并，使目标更多我想要的。

WITH t2 
AS 
(
SELECT * 
FROM WeatherHourly t 
WHERE EXISTS 
(
SELECT * FROM #WeatherHourly r WHERE t.EffectiveDateTime = r.EffectiveDateTime AND t.Pk_Id = r.Pk_Id 
) 
) 
MERGE t2 
AS Target 
USING #WeatherHourly 
AS Source 
ON Target.Pk_Id = Source.Pk_Id 
    AND Target.EffectiveDateTime = Source.EffectiveDateTime 
WHEN MATCHED THEN 
    UPDATE SET Target.Value = Source.Value,Target.ObservationDateTime = Source.ObservationDateTime 
WHEN NOT MATCHED BY TARGET THEN 
    INSERT ([Pk_Id],[ObservationDateTime],[EffectiveDateTime],[Value]) 
    VALUES (SourcePk_Id,Source.ObservationDateTime,Source.EffectiveDateTime,Source.Value) 
WHEN NOT MATCHED BY SOURCE THEN 
    DELETE; 

这似乎是在做我想要的。任何批评都会有所帮助。很抱歉，任何人要解决这个代码搞砸了。

Answer 1

WITH t2 
AS 
(
SELECT * FROM WeatherHourly t 
WHERE EXISTS 
(
SELECT * FROM #WeatherHourly r WHERE t.EffectiveDateTime = r.EffectiveDateTime AND t.Pk_Id = r.Pk_Id 
) 
) 
MERGE t2 
AS Target 
USING #WeatherHourly 
AS Source 
ON Target.Pk_Id = Source.Pk_Id 
    AND Target.EffectiveDateTime = Source.EffectiveDateTime 
WHEN MATCHED THEN 
    UPDATE SET Target.Value = Source.Value,Target.ObservationDateTime = Source.ObservationDateTime 
WHEN NOT MATCHED BY TARGET THEN 
    INSERT ([Pk_Id],[ObservationDateTime],[EffectiveDateTime],[Value]) 
    VALUES (SourcePk_Id,Source.ObservationDateTime,Source.EffectiveDateTime,Source.Value) 
WHEN NOT MATCHED BY SOURCE THEN 
    DELETE; 

测试之后似乎运作良好。

Answer 2

为什么不删除预先存在的EffectiveDateTime，然后插入新的？

DELETE FROM WeatherHourly 
WHERE EffectiveDateTime = (SELECT TOP(1) 
            EffectiveDateTime 
           FROM 
            #WeatherHourly) 


INSERT INTO WeatherHourly 
(
    [Pk_Id] 
    ,[ObservationDateTime] 
    ,[EffectiveDateTime] 
    ,[Value] 
) 
SELECT 
    [Pk_Id] 
    ,[ObservationDateTime] 
    ,[EffectiveDateTime] 
    ,[Value] 
FROM 
    #WeatherHourly