删除重复数据，保留一行

-- 删除某几列相同的，重复数据
delete from Process.SSC_HqItemConfig 
WHERE 
ID NOT IN
(
    select min(ID) from Process.SSC_HqItemConfig group by CompanyCode, FlowCode, ActivityType, BusinessCode  
    having count(CompanyCode)>1
) 
AND 
exists 
( 
    -- 匹配原来某些列    
       

   select * from (
    SELECT CompanyCode, FlowCode, ActivityType, BusinessCode 
    FROM Process.SSC_HqItemConfig b
    GROUPby CompanyCode, FlowCode, ActivityType, BusinessCode 
    having count(CompanyCode) >1

    ) b 

    WHERE b.CompanyCode = CompanyCode AND b.FlowCode = FlowCode

    AND b.ActivityType = ActivityType AND b.ActivityType = ActivityType

)