PDO通过参考通知吗? [英] PDO pass by reference notice?

问题描述

此:

$stmt = $dbh->prepare("SELECT thing FROM table WHERE color = :color");
$stmt->bindParam(':color', $someClass->getColor());
$stmt->execute();

得出这样的结果:

运行时通知
仅应传递变量 参考

Runtime notice
Only variables should be passed by reference

尽管它仍然执行.

此:

$stmt = $dbh->prepare("SELECT thing FROM table WHERE color = :color");
$tempColor = $someClass->getColor();
$stmt->bindParam(':color',$tempColor);
$stmt->execute();

运行无投诉.

我不明白区别吗?

推荐答案

bindParam的第二个参数是变量参考.由于无法引用函数返回，因此它不能严格满足bindParam参数的需求(尽管PHP可以与您一起使用，并且只会在此处发出警告).

The second parameter of bindParam is a variable reference. Since a function return cannot be referenced, it fails to strictly meet the needs of the bindParam parameter (PHP will work with you though and will only issue a warning here).

为获得更好的主意，请参见以下示例:此代码将产生与您的第二个示例相同的结果:

To get a better idea, here's and example: this code will produce the same results as your second example:

$stmt = $dbh->prepare("SELECT thing FROM table WHERE color = :color");
$tempColor = NULL; // assigned here
$stmt->bindParam(':color',$tempColor);
$tempColor = $someClass->getColor(); // but reassigned here
$stmt->execute();

使用函数返回将无法实现.

That won't be possible with a function return.

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