结合来自多个表的更新查询

-1

是否有可能将这2个更新查询合并到1 并且这样做是否具有任何性能优势？结合来自多个表的更新查询

update AREA 
set ID_MasterArea =AREACITY.ID_Area 
from dbo.Area AREA 
JOIN dbo.Address A on AREA.ID_Address = A.ID_Address 
JOIN dbo.Area AREACITY on A.ID_City = AREACITY.ID_City 
where AREA.ID_MasterArea IS NULL 
and AREA.ID_Address IS NOT NULL 

update AREA 
set ID_MasterArea =AREACOUNTRY.ID_Area 
from dbo.Area AREA 
JOIN dbo.City C on AREA.ID_City = c.ID_City 
JOIN dbo.Area AREACOUNTRY on C.ID_Country = AREACOUNTRY.ID_Country 
where AREA.ID_MasterArea IS NULL 
and AREA.ID_City IS NOT NULL

来源

2017-06-02 Frederik De Clercq

两个查询是不同的，所以结合更新不会是正确的选择更新前

update AREA set ID_MasterArea = case when Area.ID_Address is not null then AREACOUNTRY.ID_Area when Area.ID_City is not null then AreaCountry.Id_Area end from dbo.Area AREA JOIN dbo.City C on AREA.ID_City = c.ID_City LEFT JOIN dbo.Area AREACOUNTRY on C.ID_Country = AREACOUNTRY.ID_Country LEFT JOIN dbo.Address A On Area.ID_Address = A.ID_Address LEFT JOIN dbo.AREA AREACITY on A.ID_City = AREACITY.ID_City where AREA.ID_MasterArea IS NULL

检查连接 – TheGameiswar

你为什么要问？这两个查询使用不同的表格，不同的条件和不同的值。如果您想提高性能，请确保表格已编入索引。连接列至少应该由索引覆盖 –

它对我来说看起来非常重复，因为我也必须为省，城市，国家...... –

你是这样的吗？做什么记录，你要更新，并做相应的更新，如果好的

来源

2017-06-02 13:35:29

是的，这是我想要的！如果它工作:) –

结合来自多个表的更新查询

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