摘要: 笛卡尔积 3 × 2 select * from t_user, t_address; 或 select * from t_user inner join t_address; 左外链接 select * from t_user u left outer join t_address a on u. 阅读全文
posted @ 2021-01-30 14:24 风冰水 阅读(44) 评论(0) 推荐(0) 编辑