MySQL 支持四种事务隔离级别,每种级别都有其特点,并且在不同程度上解决了并发操作中可能出现的不同问题,比如脏读、不可重复读和幻读。下面是这四种隔离级别的介绍: 读未提交(Read Uncommitted) 特点&#…
情态动词种类
1、can could 2、will would 3、may might 4、must have to 5、shall should ought to be supposed to do 6、need dare
表能力 can you can speak English. could(can的过去式) you could speak English. (表达过去能说英语…