1.read uncommitted：读未提交
演示：
set global transaction isolation level read uncommitted；
start transaction;
- - 转账操作
update account set balance = balance - 500 where id = 1;
update account set balance = balance +500 where id = 2;
在开一个窗口
read committed：读已提交（Oracle)
set global transaction isolation level read committed；
start transaction;
转账操作
update account set balance = balance - 500 where id = 1;
update account set balance = balance +500 where id = 2;
在开一个窗口
事务_事务隔离级别演示2
set global transaction isolation level repeatable read;
start transaction;
转账操作
update account set balance = balance - 500 where id = 1;
update account set balance = balance +500 where id = 2;
在开启一个窗口
serializable锁
set global transaction isolation level serializable;
start transaction;
转账操作
update account set balance = balance - 500 where id = 1;
update account set balance = balance +500 where id = 2;
在开一窗口
