mysql数据库教程：using用来指定连接字段
mysql数据库教程：using用来指定连接字段代码如下：
mysql> select * from stuinfo inner join stumarks using(stuno);
+--------+----------+--------+--------+---------+------------+---------+-------------+---------+
| stuNo| stuName| stuSex | stuAge | stuSeat | stuAddress | examNo| writtenExam | labExam |
+--------+----------+--------+--------+---------+------------+---------+-------------+---------+
| s25303 | 李斯文 | 女 | 22 | 2 | 北京 | s271811 | 80 | 58 |
| s25302 | 李文才 | 男 | 31 | 3 | 上海 | s271813 | 50 | 90 |
| s25304 | 欧阳俊雄 | 男 | 28 | 4 | 天津 | s271815 | 65 | 50 |
| s25301 | 张秋丽 | 男 | 18 | 1 | 北京 | s271816 | 77 | 82 |
| s25318 | 争青小子 | 男 | 26 | 6 | 天津 | s271819 | 56 | 48 |
+--------+----------+--------+--------+---------+------------+---------+-------------+---------+
5 rows in set (0.00 sec)using的结果也会对公共字段进行优化，优化的规则和自然连接是一样的。
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