mysql - php pdo 缺省错误模式 和 例外模式,差不多,为什么弄两个?
先说 缺省模式
<code>$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_SILENT);</code>
我做的实验中,出错后,会给 $pdo->errorCode() 和 $pdo->errorInfo() 赋值;通过调用他们可以可以 看 错误的详细信息;
然后说例外模式
<code>$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
try{
}catch(PDOException $e){
echo "执行命令失败：".$e->getMessage();
exit;
}</code>会实例出一个 $e 对象,错误信息保存在这个属性里.
都是有错误信息,为什么要分两个属性?
回复内容：
先说 缺省模式
<code>$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_SILENT);</code>
我做的实验中,出错后,会给 $pdo->errorCode() 和 $pdo->errorInfo() 赋值;通过调用他们可以可以 看 错误的详细信息;
然后说例外模式
<code>$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
try{
}catch(PDOException $e){
echo "执行命令失败：".$e->getMessage();
exit;
}</code>会实例出一个 $e 对象,错误信息保存在这个属性里.
都是有错误信息,为什么要分两个属性?
/*错误模式说明:
<code>
◆异常模式:
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
这个模式需要配合 try 使用 :
一旦出错,就会:
1.创建一个对象,$e 也可以随便命名,从 $e->getMessage() 获取错误信息;
2.采取动作;
try{
要执行的命令...
}catch(PDOException $e){
echo "执行命令失败：".$e->getMessage();
失败后的动作...
}
这个其实等于 ◆缺省模式的 if($pdo->errorInfo()[2]) ...
创建PDO的时候,为什么也用 try?
因为这时候连PDO对象都没有,所以也不能设置错误模式,所以可以用try,
一旦PDO创建成功,错误模式就成了 ◆缺省模式,
也就不能用try了.
</code><code>◆缺省模式:
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_SILENT);
这个出错,会给 $pdo->errorCode() 和 $pdo->errorInfo()[2] 赋值;
可以用
if($pdo->errorInfo()[2])
if($pdo->errorCode())
判断脚本是不是出错.
如果不出错,上面都是空的;
</code><code>◆警告模式:
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_WARNING);
这个会echo出一个错误信息,打乱了脚本;
学习调试的时候使用比较好;
真用起来的时候,很多时候判断不出到底脚本有没有出错;
</code>*/
你太纠结了...这是为了方便使用者，为啥一定要有个为什么。就像是有些API通过参数可以选择返回json还是xml，有什么特别的意义吗？也是为了方便而已。
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