从函数调用PDO [英] Call PDO from a function
问题描述
此函数从数据库返回一行并将其打印在浏览器中.
<?php
$an_int = 12;
// If this is an integer
if (is_int($an_int))
{
$conn = new PDO('mysql:host=localhost;dbname=pushchat', 'pushchat', 'd]682\#%yI1nb3');
global $conn;
$stmt = $conn->prepare("SELECT IdPhoto, device_token, IdUser FROM photos ORDER BY IdPhoto DESC LIMIT 300 ");
$stmt->execute();
$result = $stmt->fetch(PDO::FETCH_ASSOC);
print_r($result);
}
?>
如何从标准功能中调用上述代码?现在浏览器还没有输出任何东西.
<?php
function new_function()
{
$an_int = 12;
// If this is an integer
if (is_int($an_int))
{
$conn = new PDO('mysql:host=localhost;dbname=pushchat', 'pushchat', 'd]682\#%yI1nb3');
global $conn;
$stmt = $conn->prepare("SELECT IdPhoto, device_token, IdUser FROM photos ORDER BY IdPhoto DESC LIMIT 300 ");
$stmt->execute();
$result = $stmt->fetch(PDO::FETCH_ASSOC);
print_r($result);
}
}
new_function();
?>
浏览器不显示此当前语法的输出.有什么方法可以从new_function函数内部调用我的原始代码吗?有什么想法吗?
好吧，在您的第一个文件中，您已经声明了global变量global $conn;我不完全知道为什么，但是无论如何都可以正常工作，因为$ conn在全球范围内.
但是在第二种情况下，当您在函数内声明global变量时，该函数将搜索位于全局范围内的$conn而不是显然具有连接句柄的局部变量$conn.
从功能中删除global $conn，它应该可以工作.
有关可变范围的更多信息- http://php.net/manual/zh/language.variables.scope.php
This function returns a row from the database and prints it in the browser.
<?php
$an_int = 12;
// If this is an integer
if (is_int($an_int))
{
$conn = new PDO('mysql:host=localhost;dbname=pushchat', 'pushchat', 'd]682\#%yI1nb3');
global $conn;
$stmt = $conn->prepare("SELECT IdPhoto, device_token, IdUser FROM photos ORDER BY IdPhoto DESC LIMIT 300 ");
$stmt->execute();
$result = $stmt->fetch(PDO::FETCH_ASSOC);
print_r($result);
}
?>
How can one call the above code from a standard fucntion? Right now the browser doesn't output anything yet.
<?php
function new_function()
{
$an_int = 12;
// If this is an integer
if (is_int($an_int))
{
$conn = new PDO('mysql:host=localhost;dbname=pushchat', 'pushchat', 'd]682\#%yI1nb3');
global $conn;
$stmt = $conn->prepare("SELECT IdPhoto, device_token, IdUser FROM photos ORDER BY IdPhoto DESC LIMIT 300 ");
$stmt->execute();
$result = $stmt->fetch(PDO::FETCH_ASSOC);
print_r($result);
}
}
new_function();
?>
The browser does not show output with this current syntax. Is there a way to call my original code from inside the new_function function... any ideas?
Well, in your first file you have declared a global variable global $conn; I don't exactly know why but anyway that would work without any issue because $conn is in global scope.
But in your second case when you declare your global variable inside a function, the function would search for $conn which is in global scope instead of the local variable $conn which apparently has the connection handle.
remove the global $conn from your function and it should work.
more information on variable scopes - http://php.net/manual/en/language.variables.scope.php
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