packageorg.springframework.transaction.annotation;public enumIsolation { DEFAULT(-1), READ_UNCOMMITTED(1), READ_COMMITTED(2), REPEATABLE_READ(4), SERIALIZABLE(8);private final intvalue;private Isolation(intvalue) {this.value =value; }public intvalue() {return this.value; } } 1. 2. 3. 4....
[LIMIT [offset,] rows] [PROCEDURE procedure_name]] 从这个基本语法可以看出,最简单的SELECT语句是SELECT select_list,实际上利用这个最简单的SELECT语句,你也可以完成许多你期待的功能,首先你能利用它进行MySQL所支持的任何运算,例如:SELECT 1+1,它将返回2;其次,你也能利用它给变量赋值,而在PHP中,运用SELECT语...
In REPEATABLE-READ isolation level, the phenomenon of non-repeatable read is avoided. It is the default isolation in MySQL.This isolation level returns the same result set throughout the transaction execution for the same SELECT run any number of times during the progression of a transaction. Thi...
7)B表重新开始事务后,对user表记录进行修改,修改被挂起,直至超时,但是对另一条数据的修改成功,说明A的修改对user表的数据行加行共享锁(因为可以使用select) 可以看出READ-UNCOMMITTED隔离级别,当两个事务同时进行时,即使事务没有提交,所做的修改也会对事务内的查询做出影响,这种级别显然很不安全。但是在表对某行进...
When using the defaultREPEATABLE READisolation level, the firstUPDATEacquires an x-lock on each row that it reads and does not release any of them: x-lock(1,2); retain x-lock x-lock(2,3); update(2,3) to (2,5); retain x-lock x-lock(3,2); retain x-lock x-lock(4,3); upd...
最低的隔离级别，事务中的修改操作对其他事务是可见的，即未提交的修改可以被其他事务读取。存在脏读（...
17.7.2.1 Transaction Isolation Levels InnoDBoffers all four transaction isolation levels described by the SQL:1992 standard:READ UNCOMMITTED,READ COMMITTED,REPEATABLE READ, andSERIALIZABLE. The default isolation level forInnoDBisREPEATABLE READ. A user can change the isolation level for a single session ...
CREATE TABLE `account` ( `id` int(11) NOT NULL AUTO_INCREMENT, `name` varchar(255) DEFAULT NULL, `balance` int(11) DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8; INSERT INTO `test`.`account` (`name`, `balance`) VALUES ('lilei', '450'); INSERT INTO `...
CREATETABLE`cs`(`id`int(10)unsignedNOTNULLAUTO_INCREMENT,`num`int(10)NOTNULLDEFAULT'0',PRIMARYKEY(`id`))ENGINE=InnoDBAUTO_INCREMENT=1DEFAULTCHARSET=utf8mb4COLLATE=utf8mb4_unicode_ci; 事务的分类 显示事务: read write:读写事务,默认模式,表示当前事务可以读写数据。
given at all, the default is 'auto'. --character-sets-dir=name Directory for character set files. -d, --database=name List entries for just this database (local log only). --debug-check Check memory and open file usage at exit . ...