mysql, mariadb删库、恢复的完整模拟实现
模拟修改和删除操作；MariaDB > select * from students;
+-------+---------------+-----+--------+---------+-----------+
| StuID | Name | Age | Gender | ClassID | TeacherID |
+-------+---------------+-----+--------+---------+-----------+
| 1 | Shi Zhongyu |22 | M | 2 | 3 |
| 2 | Shi Potian |22 | M | 1 | 7 |
| 3 | Xie Yanke |53 | M | 2 | 16 |
| 4 | Ding Dian |32 | M | 4 | 4 |
| 5 | Yu Yutong |26 | M | 3 | 1 |
| 6 | Shi Qing |46 | M | 5 | NULL |
| 7 | Xi Ren |19 | F | 3 | NULL |
| 8 | Lin Daiyu |17 | F | 7 | NULL |
| 9 | Ren Yingying|20 | F | 6 | NULL |
| 10 | Yue Lingshan|19 | F | 3 | NULL |
| 11 | Yuan Chengzhi |23 | M | 6 | NULL |
| 12 | Wen Qingqing|19 | F | 1 | NULL |
| 13 | Tian Boguang|33 | M | 2 | NULL |
| 14 | Lu Wushuang |17 | F | 3 | NULL |
| 15 | Duan Yu |19 | M | 4 | NULL |
| 16 | Xu Zhu |21 | M | 1 | NULL |
| 17 | Lin Chong |25 | M | 4 | NULL |
| 18 | Hua Rong |23 | M | 7 | NULL |
| 19 | Xue Baochai |18 | F | 6 | NULL |
| 20 | Diao Chan |19 | F | 7 | NULL |
| 21 | Huang Yueying |22 | F | 6 | NULL |
| 22 | Xiao Qiao |20 | F | 1 | NULL |
| 23 | Ma Chao |23 | M | 4 | NULL |
| 24 | Xu Xian |27 | M | NULL | NULL |
| 25 | Sun Dasheng | 100 | M | NULL | NULL |
+-------+---------------+-----+--------+---------+-----------+
25 rows in set (0.00 sec)
MariaDB > insert into students (name,age,gender) values('a','29','F');
Query OK, 1 row affected (0.01 sec)
MariaDB > select * from students;
+-------+---------------+-----+--------+---------+-----------+
| StuID | Name | Age | Gender | ClassID | TeacherID |
+-------+---------------+-----+--------+---------+-----------+
| 1 | Shi Zhongyu |22 | M | 2 | 3 |
| 2 | Shi Potian |22 | M | 1 | 7 |
| 3 | Xie Yanke |53 | M | 2 | 16 |
| 4 | Ding Dian |32 | M | 4 | 4 |
| 5 | Yu Yutong |26 | M | 3 | 1 |
| 6 | Shi Qing |46 | M | 5 | NULL |
| 7 | Xi Ren |19 | F | 3 | NULL |
| 8 | Lin Daiyu |17 | F | 7 | NULL |
| 9 | Ren Yingying|20 | F | 6 | NULL |
| 10 | Yue Lingshan|19 | F | 3 | NULL |
| 11 | Yuan Chengzhi |23 | M | 6 | NULL |
| 12 | Wen Qingqing|19 | F | 1 | NULL |
| 13 | Tian Boguang|33 | M | 2 | NULL |
| 14 | Lu Wushuang |17 | F | 3 | NULL |
| 15 | Duan Yu |19 | M | 4 | NULL |
| 16 | Xu Zhu |21 | M | 1 | NULL |
| 17 | Lin Chong |25 | M | 4 | NULL |
| 18 | Hua Rong |23 | M | 7 | NULL |
| 19 | Xue Baochai |18 | F | 6 | NULL |
| 20 | Diao Chan |19 | F | 7 | NULL |
| 21 | Huang Yueying |22 | F | 6 | NULL |
| 22 | Xiao Qiao |20 | F | 1 | NULL |
| 23 | Ma Chao |23 | M | 4 | NULL |
| 24 | Xu Xian |27 | M | NULL | NULL |
| 25 | Sun Dasheng | 100 | M | NULL | NULL |
| 26 | a |29 | F | NULL | NULL |
+-------+---------------+-----+--------+---------+-----------+
26 rows in set (0.00 sec)
MariaDB >
MariaDB > drop database hellodb ;
Query OK, 7 rows affected (0.01 sec)
MariaDB [(none)]> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| test |
+--------------------+
4 rows in set (0.00 sec)
MariaDB [(none)]> use test;
Database changed
MariaDB > create table t1(id int);
Query OK, 0 rows affected (0.01 sec)
MariaDB > select * from test;
ERROR 1146 (42S02): Table 'test.test' doesn''t exist
MariaDB >
MariaDB > show tables;
+----------------+
| Tables_in_test |
+----------------+
| t1 |
+----------------+
1 row in set (0.00 sec)
MariaDB > flush tables with read lock;
Query OK, 0 rows affected (0.00 sec)
MariaDB > select * from t1;
Empty set (0.00 sec)
MariaDB > insert t1 values(1);
ERROR 1223 (HY000): Can''t execute the query because you have a conflicting read lock
MariaDB >
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