因为你的MySQL版本中GROUP BY 的语法要求SELECT后面的字段不能超出GROUP BY 要排序的字段集，否则就会返回SELECT list is not in GROUP BY clause的错误，而你用min（）函数之后返回的是一个值，SELECT 后面就只有goods_name一个字段了，这样就会跟GROUP BY 后面的goods_name字段对应上，查询语句就可以正确执行了。

这个sql语句违背了sql_mode=only_full_group_by 

在cmd上

set @@sql_mode='STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION';

去掉ONLY_FULL_GROUP_BY即可正常执行sql.

 from tdb_goods a group by goods

多写了个a…

 from tdb_goods group by goods

delete t1 from tdb_goods as t1 left join (select min(a.goods_id)goods_id,goods_name from tdb_goods a group by goods_name having count(goods_name)>1) t2
on t1.goods_name = t2.goods_name
where t1.goods_id > t2.goods_id

a是干嘛的？