SQL 删除重复数据

delete from dbo.CompanyInfo where CompanyName in (select  CompanyName from CompanyInfo group by CompanyName   having  count(CompanyName) > 1) and CompanyID not in (select min(CompanyID) from CompanyInfo  group by CompanyName  having count(CompanyName)>1)

思路大概是 先找出有重复数据的项  然后取出重复数据项里ID号最小的项！