+---------+------------+----------+--------------+-------------+-----------+----
---------+----------+--------+------+------------+---------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Car
dinality | Sub_part | Packed | Null | Index_type | Comment |
+---------+------------+----------+--------------+-------------+-----------+----
---------+----------+--------+------+------------+---------+
| mytable | 0 | PRIMARY | 1 | id | A |
14 | NULL | NULL | | BTREE | |
+---------+------------+----------+--------------+-------------+-----------+----
---------+----------+--------+------+------------+---------+
1 row in set (0.00 sec)
#根据文档介绍，如果只有一个索引，那么replace相当于insert.
##记得我曾经创建了两个表,现在我们切换到另一个数据较少的表mytab上进行操作演示：
mysql> show tables;
+----------------+
| Tables_in_mydb |
+----------------+
| mytab |
+----------------+
2 rows in set (0.00 sec)
#其默认的索引为id
mysql> show index from mytab;
+-------+------------+----------+--------------+-------------+-----------+------
-------+----------+--------+------+------------+---------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardi
nality | Sub_part | Packed | Null | Index_type | Comment |
+-------+------------+----------+--------------+-------------+-----------+------
-------+----------+--------+------+------------+---------+
| mytab | 0 | PRIMARY | 1 | id | A |
3 | NULL | NULL | | BTREE | |
+-------+------------+----------+--------------+-------------+-----------+------
-------+----------+--------+------+------------+---------+
1 row in set (0.00 sec)
#现在需要向其中添加索引(在这里遇到麻烦了，看来我对于建立索引不怎么会啊，惭愧惭愧)。
#尝试建立了多个索引都是失败，暂时写到这里。。。。
写这些并非上班不务正业，而是公司具体任务被安排到下周，接下来该忙了。