6.9 mysql 预处理
实验一：传入一个值
mysql> prepare stu_pre from 'select * from student where id>?';
Query OK, 0 rows affected (0.00 sec)
Statement prepared
mysql> set @i=3;
Query OK, 0 rows affected (0.00 sec)
mysql> select @i;
+------+
| @i |
+------+
| 3 |
+------+
1 row in set (0.00 sec)
mysql> execute stu_pre using @i;
+------+------+------+-------+
| id | name | sex | score |
+------+------+------+-------+
| 4 | dd | male | 3.5 |
| 5 | ee | male | 3.6 |
| 6 | ff | male | 3.9 |
+------+------+------+-------+
3 rows in set (0.00 sec)
实验二：传入多个值
mysql> select * from student;
+------+------+--------+-------+
| id | name | sex | score |
+------+------+--------+-------+
| 1 | aa | female | NULL |
| 2 | bb | male | NULL |
| 3 | cc | male | 3.1 |
| 4 | dd | male | 3.5 |
| 5 | ee | male | 3.6 |
| 6 | ff | male | 3.9 |
+------+------+--------+-------+
mysql> set @id=3;
Query OK, 0 rows affected (0.00 sec)
mysql> set @sex='male';
Query OK, 0 rows affected (0.00 sec)
mysql> prepare stu_pre from 'select * from student where id<? and sex=?';
Query OK, 0 rows affected (0.00 sec)
Statement prepared
mysql> execute stu_pre using @id,@sex;
+------+------+------+-------+
| id | name | sex | score |
+------+------+------+-------+
| 2 | bb | male | NULL |
+------+------+------+-------+
1 row in set (0.00 sec)
实验三：删除预处理
mysql> execute stu_pre using @id,@name;
+------+------+------+-------+
| id | name | sex | score |
+------+------+------+-------+
| 2 | bb | male | NULL |
+------+------+------+-------+
1 row in set (0.00 sec)
mysql> drop prepare stu_pre;
Query OK, 0 rows affected (0.00 sec)
mysql> execute stu_pre using @id,@name;
ERROR 1243 (HY000): Unknown prepared statement handler (stu_pre) given to EXECUTE
6.10 mysql 事务处理
MyISAM引擎不支持事务，innodb支持事务
修改表引擎：
mysql> show create table student;
+---------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+---------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| student | CREATE TABLE `student` (
`id` int(11) DEFAULT NULL,
`name` varchar(30) DEFAULT NULL,
`sex` varchar(10) DEFAULT NULL,
`score` float DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1 |
+---------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
mysql> alter table student engine=innodb;
Query OK, 4 rows affected (0.05 sec)
Records: 4 Duplicates: 0 Warnings: 0
mysql> show create table student;
+---------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+---------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| student | CREATE TABLE `student` (
`id` int(11) DEFAULT NULL,
`name` varchar(30) DEFAULT NULL,
`sex` varchar(10) DEFAULT NULL,
`score` float DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+---------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
6.10.1 关闭自动提交功能
set autocommit=0;
6.10.2 保存还原点
savepoint pointName;
6.10.3 还原至某个点
rollback to pointName;
6.10.4 还原到原始点
rollback
实验一：
#设置事务不自动提交
mysql> set autocommit=0;
Query OK, 0 rows affected (0.00 sec)
mysql> select * from student;
+------+------+--------+-------+
| id | name | sex | score |
+------+------+--------+-------+
| 1 | aa | female | NULL |
| 2 | bb | male | NULL |
| 3 | cc | male | 3.1 |
| 6 | ff | male | 3.9 |
+------+------+--------+-------+
4 rows in set (0.00 sec)
#删除id=1的数据
mysql> delete from student where id=1;
Query OK, 1 row affected (0.00 sec)
#设置还原点
mysql> savepoint p1;
Query OK, 0 rows affected (0.00 sec)
#可以看到id=1的数据已经消失
mysql> select * from student;
+------+------+------+-------+
| id | name | sex | score |
+------+------+------+-------+
| 2 | bb | male | NULL |
| 3 | cc | male | 3.1 |
| 6 | ff | male | 3.9 |
+------+------+------+-------+
3 rows in set (0.00 sec)
#再删除id=2的数据
mysql> delete from student where id=2;
Query OK, 1 row affected (0.00 sec)
#设置还原点
mysql> savepoint p2;
Query OK, 0 rows affected (0.00 sec)
#可以看到id=5的数据已经消失
mysql> select * from student;
+------+------+------+-------+
| id | name | sex | score |
+------+------+------+-------+
| 3 | cc | male | 3.1 |
| 6 | ff | male | 3.9 |
+------+------+------+-------+
2 rows in set (0.00 sec)
#回滚至第一个还原点
mysql> rollback to p1;
Query OK, 0 rows affected (0.00 sec)
#可以看到id=2的数据恢复了
mysql> select * from student;
+------+------+------+-------+
| id | name | sex | score |
+------+------+------+-------+
| 2 | bb | male | NULL |
| 3 | cc | male | 3.1 |
| 6 | ff | male | 3.9 |
+------+------+------+-------+
3 rows in set (0.00 sec)
#回滚到初始点
mysql> rollback;
Query OK, 0 rows affected (0.01 sec)
#可见数据全部恢复
mysql> select * from student;
+------+------+--------+-------+
| id | name | sex | score |
+------+------+--------+-------+
| 1 | aa | female | NULL |
| 2 | bb | male | NULL |
| 3 | cc | male | 3.1 |
| 6 | ff | male | 3.9 |
+------+------+--------+-------+
4 rows in set (0.00 sec)
#提交事务
mysql> commit ;
Query OK, 0 rows affected (0.00 sec)
mysql> select * from student;
+------+------+--------+-------+
| id | name | sex | score |
+------+------+--------+-------+
| 1 | aa | female | NULL |
| 2 | bb | male | NULL |
| 3 | cc | male | 3.1 |
| 6 | ff | male | 3.9 |
+------+------+--------+-------+
4 rows in set (0.00 sec)
注意：再进行实验时需要将事务的自动提交关闭，否则不能进行该实验。