Question

我有commFun.php用于commong函数;

<?php

function connectDB(){
    $con = @mysqli_connect( "localhost:3306", "root", "P@ssw0rd", "DogSport" ) or die ("Couldn't connect to server");
}

//check that email is not already in list
function emailChecker( $email ){
    connectDB();

    $safe_email = mysqli_real_escape_string( $con, $email );
    $check_sql = "SELECT Id FROM Subscribers WHERE Email='". $safe_email. "'";

    $result = mysqli_query ( $con, $check_sql ) or die ("Couldn't execute SELECT query: ". mysqli_error($con));
}
?>

当我从另一个PHP脚本调用emailChecker（）函数时，为什么connectDB（）中的$ con变量不可用于emailChecker（）函数？我已经在emailChecker（）函数中调用了connectDB（）函数？我究竟做错了什么？？？？？

我收到以下错误;

 Notice: Undefined variable: con in C:\xampp\htdocs\PHP\commonFun.php on line 11

Warning: mysqli_real_escape_string() expects parameter 1 to be mysqli, null given in C:\xampp\htdocs\PHP\commonFun.php on line 11

Notice: Undefined variable: con in C:\xampp\htdocs\PHP\commonFun.php on line 14

Warning: mysqli_query() expects parameter 1 to be mysqli, null given in C:\xampp\htdocs\PHP\commonFun.php on line 14

Notice: Undefined variable: con in C:\xampp\htdocs\PHP\commonFun.php on line 14

Warning: mysqli_error() expects parameter 1 to be mysqli, null given in C:\xampp\htdocs\PHP\commonFun.php on line 14
Couldn't execute SELECT query:

Answer 1

糟糕的解决方案，但它会起作用：

function connectDB(){
    global $con;

    $con = @mysqli_connect( "localhost:3306", "root", "P@ssw0rd", "DogSport" ) or die ("Couldn't connect to server");
}

//check that email is not already in list
function emailChecker( $email ){
    global $con;

    connectDB();

    $safe_email = mysqli_real_escape_string( $con, $email );
    $check_sql = "SELECT Id FROM Subscribers WHERE Email='". $safe_email. "'";

    $result = mysqli_query ( $con, $check_sql ) or die ("Couldn't execute SELECT query: ". mysqli_error($con));
}

另一种解决方案：

$con = @mysqli_connect( "localhost:3306", "root", "P@ssw0rd", "DogSport" ) or die ("Couldn't connect to server");

//check that email is not already in list
function emailChecker( $email ){
    global $con;

    $safe_email = mysqli_real_escape_string( $con, $email );
    $check_sql = "SELECT Id FROM Subscribers WHERE Email='". $safe_email. "'";

    $result = mysqli_query ( $con, $check_sql ) or die ("Couldn't execute SELECT query: ". mysqli_error($con));
}

在脚本中的每个函数调用中调用mysqli_connect（）都很糟糕。每次执行页面时，您必须只连接一次数据库。

Answer 2

function connectDB（）{

$ con = @mysqli_connect（“localhost：3306”，“root”，“P @ ssw0rd”，“DogSport”）或死亡（“无法连接到服务器”）;

返回$ con; }

PHP使用include（）变量范围问题

2 个答案: