开启事务的三种方式：
1.在此线程内有效，上一事务结束后，立刻自动开启新的事物
mysql> set autocommit = 0;2.临时开启
mysql> begin;3.临时开启
mysql> start transaction;提交事务：
mysql> commit;回滚事务：
mysql> rollback;插入保存点：
mysql> savepoint a;插入后，再回滚到a时，意味着a之后的语句全部失效
mysql> begin;
Query OK, 0 rows affected (0.00 sec)
mysql> insert into jdbc_test values(null,"li","jkhsdfjdgh");
Query OK, 1 row affected (0.02 sec)
mysql> savepoint a;
Query OK, 0 rows affected (0.02 sec)
mysql> insert into jdbc_test values(null,"wang","45456456");
Query OK, 1 row affected (0.00 sec)
mysql> savepoint b;
Query OK, 0 rows affected (0.00 sec)
mysql> select * from jdbc_test;
+---------+-----------+---------------------+
| jdbc_id | jdbc_name | jdbc_desc |
+---------+-----------+---------------------+
| 1 | kobe | twotimesmvp |
| 2 | levin | arookie |
| 3 | jodan | mvp of the history |
| 4 | kobe | two times mvp |
| 5 | levin | a rookie |
| 6 | jodan | mvp of the history |
| 7 | mcgrady | two times defenwang |
| 8 | shaq | rebound |
| 10 | lebron | mvp |
| 11 | bird | mop |
| 12 | li | jkhsdfjdgh |
| 13 | wang | 45456456 |
+---------+-----------+---------------------+
12 rows in set (0.00 sec)
mysql> rollback to a;
Query OK, 0 rows affected (0.00 sec)
mysql> select * from jdbc_test;
+---------+-----------+---------------------+
| jdbc_id | jdbc_name | jdbc_desc |
+---------+-----------+---------------------+
| 1 | kobe | twotimesmvp |
| 2 | levin | arookie |
| 3 | jodan | mvp of the history |
| 4 | kobe | two times mvp |
| 5 | levin | a rookie |
| 6 | jodan | mvp of the history |
| 7 | mcgrady | two times defenwang |
| 8 | shaq | rebound |
| 10 | lebron | mvp |
| 11 | bird | mop |
| 12 | li | jkhsdfjdgh |
+---------+-----------+---------------------+
11 rows in set (0.00 sec)