PDO函数setFetchMode [英] PDO Function setFetchMode
问题描述
你好我试图用PDO做功能,但是得到错误(新到PDO)这里是我的代码
函数mail_id ($ mail){
global $ host,$ dbname,$ user,$ pass;
$ DBH =新的PDO(mysql:host = $ host; dbname = $ dbname,$ user,$ pass);
$ STH = $ DBH->查询(从邮件中选择count(from)from ='$ mail');
$ STH-> setFetchMode(PDO :: FETCH_ASSOC);
$ row = $ STH-> fetch();
返回$ row;
$ / code>
我想计算行FROM和这是输出我正在尝试
$ mail = mail_id($ userid);
if(0< count($ mail ['to_viewed'])){echogreen;} else {echogrey;}
这是错误
调用成员函数setFetchMode()on一个非对象
请帮助thx
您需要检查的返回值 PDO ::查询()
。在(丑陋的)PHP中,有很多函数返回混合类型的值。在 PDO :: query()
的情况下,返回类型是 PDOStatement
或bool,尽管文档中的原型提供了不同的内容:
描述:
PDOStatement PDO :: query(string $ statement)
...
像它总是返回 PDOStatement
。
返回值:
PDO :: query()返回一个PDOStatement对象,或者在失败时返回FALSE。
<哎呀,不是每一种情况!因此,您不能保证返回的值是 PDOStatement
。
正确的原型是:
描述:
混合PDO :: query(string $声明)
...
在您的情况下,查询无效(通过使用保留关键字,如FROM作为列名),这会导致返回布尔型类型的值为FALSE的值。一个布尔值不是一个对象,因此你对 $ STH-> setFetchMode()
的调用失败。
根据你的PDO :: ATTR_ERRMODE,你得到了一个异常(PDO :: ERRMODE_EXCEPTION),所以你不需要检查
- b $ b返回值
- 警告(PDO :: ERRMODE_WARNING)
- nothing(PDO :: ERRMODE_SILENT),所以你必须检查返回值值,
errorCode()
和errorInfo()
Hello i was trying to make function with PDO but getting error (new to PDO) here is my code
function mail_id($mail){
global $host, $dbname, $user, $pass;
$DBH = new PDO("mysql:host=$host;dbname=$dbname", $user, $pass);
$STH = $DBH->query("select count(from) from messages where from = '$mail'");
$STH->setFetchMode(PDO::FETCH_ASSOC);
$row = $STH->fetch();
return $row;
}
i want to count row FROM and here is the out put i was trying
$mail=mail_id($userid);
if (0<count($mail['to_viewed'])) {echo "green";} else {echo "gray";}
this is the error
Call to a member function setFetchMode() on a non-object
please help thx
You need to check the return value of PDO::query()
. In (ugly) PHP there are lots of functions that return a value of mixed type. In the case of PDO::query()
the return type is either PDOStatement
or bool, although the prototype in the documentation says something different:
Description:
PDOStatement PDO::query ( string $statement )
...
Looks like it always returns PDOStatement
.
Return Values:
PDO::query() returns a PDOStatement object, or FALSE on failure.
Oops, not in every case! Therefore you are not guaranteed that the value returned is a PDOStatement
.
The correct prototype would be:
Description:
mixed PDO::query ( string $statement )
...
In your case the query is invalid (by using a reserved keyword like FROM as a column name) which results in a return value of type boolean with the value FALSE. A boolean value is not an object and therefore your call to $STH->setFetchMode()
fails.
Depending on your PDO::ATTR_ERRMODE you get
- an exception (PDO::ERRMODE_EXCEPTION), so you don't need to check the return value
- a warning (PDO::ERRMODE_WARNING)
- nothing (PDO::ERRMODE_SILENT), so you have to check the return value,
errorCode()
anderrorInfo()
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