求sql语句？（急）

[wangjungui_1983]

比较表Base_Gx_ProductsInfo中ProductsName,Trademark，ProductsModel,CompanyName这些记录是否在表Base_State_ProductsInfo中的ProductsName,Trademark，ProductsModel,CompanyName是否存在。如果存在更新表Base_Gx_ProductsInfo中的字段Status为1否则为0，现在表Base_Gx_ProductsInfo中没有CompanyName字段，他通过customerId和Base_CustomerInfo表中customerId关联，如何关联上Base_CustomerInfo表中存在CompanyName。谢谢各位？

[dawugui]

update a set Status =
(case when exists (select 1 from (select b.ProductsName,b.Trademark,b.ProductsModel,c.CompanyName from b,c where b.customerId = c.customerId) m
where m.ProductsName=n.ProductsName and m.Trademark=n.Trademark and m.ProductsModel=n.ProductsModel and m.CompanyName=n.CompanyName) then 1 else 0 end)
from a n

[dawugui]

update Base_Gx_ProductsInfo set Status =
(case when exists (select 1 from (select b.ProductsName,b.Trademark,b.ProductsModel,c.CompanyName from Base_State_ProductsInfo b, Base_CustomerInfoc where b.customerId = c.customerId) m
where m.ProductsName=n.ProductsName and m.Trademark=n.Trademark and m.ProductsModel=n.ProductsModel and m.CompanyName=n.CompanyName) then 1 else 0 end)
from Base_Gx_ProductsInfo n

[SQLCenter]

update a set a.Status = case when b.ProductsName is null then 0 else 1 end from Base_Gx_ProductsInfo a
inner join Base_CustomerInfo c on a.customerId=c.customerId
left join Base_State_ProductsInfo b on a.ProductsName=b.ProductsName and a.Trademark=b.Trademark and a.ProductsModel=b.ProductsModel and c.CompanyName=b.CompanyNam