小编Dan*_*sch的帖子

UPDATE
Chemicals.dbo.ChmProductCompositions 

SET Vhap = SUM(PercentOfProduct)

FROM 
Chemicals.dbo.ChmProductCompositions  PC
JOIN Chemicals.dbo.ChmCompositionChemicals CC ON CC.ProductCompositionID = pc.ProductCompositionID
JOIN Chemicals.dbo.ChmChemicals C ON C.ChemicalID = CC.ChemicalID
WHERE IsHazardous = 1

我有上面的查询，我想知道像上面的查询一样获取总和并设置它还是每个特定的总和并设置它？

我还想知道它是否获得总和并将每个设置为总和，我如何获取每个单独项目的总和，然后将其设置为该总和？