这篇文章主要介绍了详解mysql中关于事务的处理,小编觉得挺不错的，现在分享给大家，也给大家做个参考。一起跟随小编过来看看吧
步骤：
1.开启事务 start transaction
当我们开启一个事务的时候，我们对sql的操作都发生在内存中，但是没有真正的反馈到数据库磁盘的文件中！
2.回滚 rollback
回滚，就是恢复到事务开启之前的最原始的状态！
注意：回滚操作会自动的关闭一个事务，如果想再次执行事务，需要重新开启事务！
3.提交 commit
事务的基本原理
普通的执行，之所以是立即执行并生效，因为默认的，MySQL对sql语句的执行是自动提交的！所以，开启一个事务的本质，就是关闭了以前的自动提交的功能，而是由用户手动提交（利用commit语句）！
总结事务的步骤：
1， 开启事务
2， 如果执行成功，就提交commit
3， 如果有任何一条sql语句执行失败，则回滚rollback！
事务处理最典型的就是借还钱。下面以张三向李四还1000元为例
首先查看数据库中各自的钱数
下面是处理还钱事务的代码：
<span style="font-size: 14px; font-family: 微软雅黑, " microsoft yahei><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height:>php </span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>/** * MySQL实现事务操作<br>*/<br><br></span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>echo</span> "<meta charset="utf-8">"<span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height:>;<br><br></span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>// 1 连接数据库<br></span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>$link</span> = @<span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>mysql_connect</span>('localhost','root','') or <span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>die</span>('连接数据库失败'<span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height:>);<br></span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>mysql_select_db</span>('test',<span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>$link</span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height:>);</span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>mysql_query</span>('set names utf8'<span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height:>);<br><br></span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>// 2 开启事务<br></span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>mysql_query</span>("start transaction"<span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height:>);<br></span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>//设置一个变量，用来判断所有sql语句是否成功<br></span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>$flag</span> = <span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>true</span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height:>;<br><br></span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>// 2.1执行事务中的一组sql语句 <br><br>// 李四的money+1000<br></span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>$sql</span> = "update pdo set mone=money+1000 where name='李四'"<span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height:>;<br></span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>$res</span> = <span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>mysql_query</span>(<span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>$sql</span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height:>);<br></span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>if</span> (!<span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>$res</span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height:>) { <br> </span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>//若sql语句执行失败，把$falg设置为false</span> <span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>$flag</span> = <span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>false</span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height:>; }<br><br></span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>//张三的money-1000<br></span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>$sql</span> = "update pdo set money=money-1000 where name='张三'"<span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height:>;<br></span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>$res</span> = <span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>mysql_query</span>(<span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>$sql</span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height:>);<br></span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>if</span> (!<span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>$res</span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height:>) { <br> </span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>//若sql语句执行失败，把$falg设置为false</span> <span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>$flag</span> = <span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>false</span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height:>; }<br><br></span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>// 2.2 判断事务是否执行成功<br></span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>if</span> (<span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>$flag</span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height:>) { <br> </span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>//所有sql语句执行成功，把sql语句提交</span> <span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>mysql_query</span>('commit'<span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height:>); </span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>echo</span> "还钱成功！"<span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height:>; }</span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>else</span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height:>{ <br> </span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>// 如其中一条执行失败，则回滚到事务开启之前的状态</span> <span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>mysql_query</span>('rollback'<span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height:>); </span><span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height: color: rgb>echo</span> "还钱失败！"<span style="font-family: 微软雅黑, " microsoft yahei font-size: margin: padding: line-height:>; }</span></span>
结果：
下面，我们故意把其中一个字段写错，看看事务是否正常处理，数据库中的钱数是否有变化！
<span style="font-size: 14px; font-family: 微软雅黑, " microsoft yahei>// 李四的money+1000<br>$sql = "update pdo set mone=money+1000 where name='李四'"; //把moeny字段错写成mone<br></span>
结果：
结果是还钱失败，并且数据库中各自的钱数没有变化，说明当某一条语句未执行成功时，事物不会提交，而会回滚，把数据恢复到开始事务之前的原始状态，这也是使用事务的作用，即只有当事务中所有sql语句全部执行成功，事务才会提交，否则会回滚！
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