oracle表中删除重复项的问题

摘要: 在tab_shop_info表中，删除cust_id(非主键)重复的项，只保留主键(shop_id)最小的项。

（这段是原创的）

今天心血来潮，针对前几天韩哥说的一个会员只能创建一个商铺的问题整理一下tab_shop_info这张表，然后准备删掉会员id(cust_id)重复的项，而且只留下重复项里面id(shop_id)最小的项。

T_T 本来以为两三行写完的东西，真正写起来居然这么复杂------赶紧赶紧记下来！

第一步：查询重复项；

select cust_id from tab_shop_info group by cust_id having count(cust_id) > 1

第二步：查询重复项里面shop_id最小的；

select min(shop_id) from tab_shop_info where cust_id in (

select cust_id from tab_shop_info group by cust_id having count(cust_id) > 1

)

第三步：统计所有重复项的shop_id；

select shop_id from tab_shop_info where cust_id in (

select cust_id from tab_shop_info group by cust_id having count(cust_id) > 1

)

第四步：排除掉shop_id最小的那个；

select shop_if from (

select shop_id from tab_shop_info where cust_id in (

select cust_id from tab_shop_info group by cust_id having count(cust_id) > 1

)

)where shop_id not in(

select min(shop_id) from tab_shop_info where cust_id in (

select cust_id from tab_shop_info group by cust_id having count(cust_id) > 1

)

)

第五步：删除

delete from tab_shop_info where shop_id in(

select shop_if from (

select shop_id from tab_shop_info where cust_id in (

select cust_id from tab_shop_info group by cust_id having count(cust_id) > 1

)

)where shop_id not in(

select min(shop_id) from tab_shop_info where cust_id in (

select cust_id from tab_shop_info group by cust_id having count(cust_id) > 1

)

)

)

OK,这样才算完工了！

但是总觉得这么写好复杂啊，如果有谁写过简单一些的写法，麻烦在下面留言告知一下哈。1+1>=2，谢谢啦！