======MySQL交易 未完成======
======MySQL交易的隔離層級======
===MySQL提供四種隔離層級===
  - Read Uncommitted
  - Read Committed
  - Repeatable Read
  - Serializable
===MySQL隔離層級Demo===
在做以下解說之前,先在MySQL的test資料庫建立一個名為QQ的資料表並插入一些資料。(目前在 MySQL 5.1.71 下作業)
<code>mysql> create table QQ(id int ,data char(10))engine=innodb;</code><code>mysql> insert into QQ(id,data)values(1,'AA'),(2,'BB'),(3,'CC'),(4,'DD'),(5,'EE'),(6,'FF'),(7,'GG'),(8,'HH'),(9,'II'),(10,'JJ');</code>
===Repeatable-Read===
^Time  ^session1                                 ^session2             ^
|      |mysql>show variables like '%iso%';                                  |mysql>show variables like '%iso%';                       |
|      |mysql>select * from QQ;                                   |mysql>select * from QQ;                     |
|      |mysql>start transaction;     |mysql>start transaction; |
|      | |mysql>update QQ set data='GGGG' where id=7;                                      |
|      |                                              |mysql>select * from QQ;|
|      |                                         |mysql>commit;         |
|      |mysql>select * from QQ;                  |                      |
|      |mysql>commit;                            |                      |
|      |mysql>select * from QQ;                  |                      |

===Read-Committed===

^Time  ^session1                                 ^session2             ^
|      |mysql>set tx_isolation='read-committed';                         ||
|      |mysql>show variables like '%iso%';       |mysql>show variables like '%iso%';|
|      |mysql>select * from QQ;                                   |mysql>select * from QQ;                     |
|      |mysql>start transaction;     |mysql>start transaction; |
|      | |mysql>update QQ set data='IIIII' where id=9;                                      |
|      |mysql>select * from QQ;                  |mysql>select * from QQ;|
|      |                                         |mysql>commit;         |
|      |mysql>select * from QQ;                  |                      |

======參考資料======
  * [[http://xyz.cinc.biz/2013/05/mysql-transaction.html|MySQL 交易功能 Transaction 整理 ]]