默认隔离级别
mysql> select @@tx_isolation;
+-----------------+ | @@tx_isolation | +-----------------+ | REPEATABLE-READ | +-----------------+ 1 row in set, 1 warning (0.00 sec)
设置隔离级别
设置read uncommitted级别：
mysql> set session transaction isolation level read uncommitted; Query OK, 0 rows affected (0.00 sec)
mysql> select @@tx_isolation; +------------------+ | @@tx_isolation | +------------------+ | READ-UNCOMMITTED | +------------------+ 1 row in set, 1 warning (0.00 sec)
设置read committed级别：
mysql> set session transaction isolation level read committed; Query OK, 0 rows affected (0.00 sec)
mysql> select @@tx_isolation; +----------------+ | @@tx_isolation | +----------------+ | READ-COMMITTED | +----------------+ 1 row in set, 1 warning (0.00 sec)
设置repeatable read级别：
mysql> set session transaction isolation level repeatable read; Query OK, 0 rows affected (0.00 sec)
mysql> select @@tx_isolation; +-----------------+ | @@tx_isolation | +-----------------+ | REPEATABLE-READ | +-----------------+ 1 row in set, 1 warning (0.00 sec)
设置serializable级别：
mysql> set session transaction isolation level serializable; Query OK, 0 rows affected (0.00 sec)
mysql> select @@tx_isolation; +----------------+ | @@tx_isolation | +----------------+ | SERIALIZABLE | +----------------+ 1 row in set, 1 warning (0.00 sec)
