我自己的习惯就是空格 打个AS很费时间的

就是用AS啊，比如这个删除多表的语句中有下划线的，就是把数据表 tdb_goods取别名为 t1啊，别名可以随便取，你觉得什么名字好就取什么名字。

DELETE t1 FROM tdb_goods AS t1  LEFT JOIN (SELECT goods_id,goods_name, FROM tdb_goods GROUP BY goods_name HAVING count(goods_name)  >=2) AS t2 ON t1.goods_name =t2.goods_name WHERE t1.goods_id > t2.goods_id;