查看InnoDB存储引擎 系统级的隔离级别 和 会话级的隔离级别：
mysql> select @@global.tx_isolation,@@tx_isolation;
+-----------------------+-----------------+
| @@global.tx_isolation | @@tx_isolation |
+-----------------------+-----------------+
| REPEATABLE-READ | REPEATABLE-READ |
+-----------------------+-----------------+
1 row in set (0.00 sec)
修改隔离级别
SET [SESSION | GLOBAL] TRANSACTION ISOLATION LEVEL {READ UNCOMMITTED | READ COMMITTED | REPEATABLE READ | SERIALIZABLE}
例如：
mysql> set global transaction isolation level read committed; //全局的
mysql> set session transaction isolation level read committed; //当前会话
