查询数据库中某一列有没有重复数据项

查询数据库中某一列有没有重复数据项：

select * from cd_stock where stock_bh in (select stock_bh from cd_stock group by stock_bh having count(stock_bh) >1 )

select * from cd_stock_item where id in (select id from cd_stock_item group by id having count(id) >1 )