mysql> show engines;
mysql> alter table t1 engine = innodb;
mysql> alter table t7 auto_increment = 100;
mysql> show table status like "t6"\G;
尝试用idb文件回复单个表，注意要恢复到原来的库里面：
1.备份ibd文件：
# cp t7.ibd t7.ibd.bak
2.删除表数据：
mysql> select * from t7 ;
+-----+------+
| i | name |
+-----+------+
| 1 | 1 |
| 2 | 2 |
| 3 | 3 |
| 6 | 1 |
| 7 | 2 |
| 8 | 3 |
| 100 | 1 |
| 101 | 2 |
| 102 | 3 |
+-----+------+
9 rows in set (0.00 sec)
mysql> delete from t7;
Query OK, 9 rows affected (0.07 sec)
mysql> select * from t7 ;
Empty set (0.00 sec)
3.正确识别ibd文件
mysql> alter table t7 discard tablespace;
4.回复ibd文件：
# mv t7.ibd.bak t7.ibd
# chown mysql. t7.ibd
# chmod 660 t7.ibd
5.正确识别手动回复的ibd文件
mysql> alter table t7 import tablespace;
Query OK, 0 rows affected, 1 warning (0.26 sec)
6.查询数据，侥幸回来了！
mysql> select * from t7 ;
+-----+------+
| i | name |
+-----+------+
| 1 | 1 |
| 2 | 2 |
| 3 | 3 |
| 6 | 1 |
| 7 | 2 |
| 8 | 3 |
| 100 | 1 |
| 101 | 2 |
| 102 | 3 |
+-----+------+
9 rows in set (0.00 sec)
mysql>
内存数据库：
mysql> create table t8 engine=memory select * from t7;
mysql> show table status like ‘t8‘\G
mysql> create index mem_hash using hash on t8 (i);
Query OK, 9 rows affected (0.03 sec)
Records: 9 Duplicates: 0 Warnings: 0
mysql> drop index mem_hash on t8;
Query OK, 9 rows affected (0.04 sec)
Records: 9 Duplicates: 0 Warnings: 0
mysql> create index mem_hash using btree on t8 (i);
Query OK, 9 rows affected (0.03 sec)
Records: 9 Duplicates: 0 Warnings: 0
mysql> show index from t8 \G