（这段是原创的）spa
今天心血来潮，针对前几天韩哥说的一个会员只能建立一个商铺的问题整理一下tab_shop_info这张表，而后准备删掉会员id(cust_id)重复的项，并且只留下重复项里面id(shop_id)最小的项。class
T_T 原本觉得两三行写完的东西，真正写起来竟然这么复杂------赶忙赶忙记下来！select
第一步：查询重复项；统计
select cust_id from tab_shop_info group by cust_id having count(cust_id) > 1查询
第二步：查询重复项里面shop_id最小的；tab
select min(shop_id) from tab_shop_info where cust_id in (di
select cust_id from tab_shop_info group by cust_id having count(cust_id) > 1vi
)co
第三步：统计全部重复项的shop_id；let
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！
可是总以为这么写好复杂啊，若是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！