Php 使用mysqli配置文件

我正在更新我的现有代码。我正在尝试使用“mysqli”连接数据库。我有以下文件：

config.php

function.php

index.php

header.php

config.php

<?php 
$database_host = 'localhost';
$database_username = 'root';
$database_password = 'root';
$database_name = 'db_name';
?>

<?php
include "config.php";
$link = mysqli_connect($database_host, $database_username, $database_password,$database_name);
if (mysqli_connect_errno())
    die('Could not connect: ' . mysqli_connect_error());
?>

<?php
function mysqlQuery($query) {
    $result = mysqli_query($link,$query); 
    return $result;
}
?>

    <?php
    include "header.php";
    include "function.php";
    $sql         =  "SELECT * FROM `posts`";
    mysqlQuery($sql);
    ?>

function mysqlQuery($query, $link) {
                          // ^ this one also
    $result = mysqli_query($link, $query); 
    return $result;
}

$sql = 'SELECT * FROM `posts`';
mysqlQuery($sql, $link);

header.php

<?php 
$database_host = 'localhost';
$database_username = 'root';
$database_password = 'root';
$database_name = 'db_name';
?>

<?php
include "config.php";
$link = mysqli_connect($database_host, $database_username, $database_password,$database_name);
if (mysqli_connect_errno())
    die('Could not connect: ' . mysqli_connect_error());
?>

<?php
function mysqlQuery($query) {
    $result = mysqli_query($link,$query); 
    return $result;
}
?>

    <?php
    include "header.php";
    include "function.php";
    $sql         =  "SELECT * FROM `posts`";
    mysqlQuery($sql);
    ?>

function mysqlQuery($query, $link) {
                          // ^ this one also
    $result = mysqli_query($link, $query); 
    return $result;
}

$sql = 'SELECT * FROM `posts`';
mysqlQuery($sql, $link);

function.php

<?php 
$database_host = 'localhost';
$database_username = 'root';
$database_password = 'root';
$database_name = 'db_name';
?>

<?php
include "config.php";
$link = mysqli_connect($database_host, $database_username, $database_password,$database_name);
if (mysqli_connect_errno())
    die('Could not connect: ' . mysqli_connect_error());
?>

<?php
function mysqlQuery($query) {
    $result = mysqli_query($link,$query); 
    return $result;
}
?>

    <?php
    include "header.php";
    include "function.php";
    $sql         =  "SELECT * FROM `posts`";
    mysqlQuery($sql);
    ?>

function mysqlQuery($query, $link) {
                          // ^ this one also
    $result = mysqli_query($link, $query); 
    return $result;
}

$sql = 'SELECT * FROM `posts`';
mysqlQuery($sql, $link);

index.php

<?php 
$database_host = 'localhost';
$database_username = 'root';
$database_password = 'root';
$database_name = 'db_name';
?>

<?php
include "config.php";
$link = mysqli_connect($database_host, $database_username, $database_password,$database_name);
if (mysqli_connect_errno())
    die('Could not connect: ' . mysqli_connect_error());
?>

<?php
function mysqlQuery($query) {
    $result = mysqli_query($link,$query); 
    return $result;
}
?>

    <?php
    include "header.php";
    include "function.php";
    $sql         =  "SELECT * FROM `posts`";
    mysqlQuery($sql);
    ?>

function mysqlQuery($query, $link) {
                          // ^ this one also
    $result = mysqli_query($link, $query); 
    return $result;
}

$sql = 'SELECT * FROM `posts`';
mysqlQuery($sql, $link);

我犯了这样的错误； “未定义变量：第行的/var/www/folder_path/function.php中的链接。” 我不知道我的代码出了什么问题。我知道这是一个非常基本的问题，但我仍然找不到解决办法。 我还尝试在function.php中添加行“require（'config.php'）；”

---

请帮忙。提前感谢。

您在这里使用了一个函数：

function mysqlQuery($link, $query) {
    $result = mysqli_query($link,$query); 
    return $result;
}

mysqlQuery($link, $sql);

在该范围内，$link是未知的，请将链接作为参数，它应该可以工作

---

您还需要传递连接，因为它超出了范围：

function.php

<?php 
$database_host = 'localhost';
$database_username = 'root';
$database_password = 'root';
$database_name = 'db_name';
?>

<?php
include "config.php";
$link = mysqli_connect($database_host, $database_username, $database_password,$database_name);
if (mysqli_connect_errno())
    die('Could not connect: ' . mysqli_connect_error());
?>

<?php
function mysqlQuery($query) {
    $result = mysqli_query($link,$query); 
    return $result;
}
?>

    <?php
    include "header.php";
    include "function.php";
    $sql         =  "SELECT * FROM `posts`";
    mysqlQuery($sql);
    ?>

function mysqlQuery($query, $link) {
                          // ^ this one also
    $result = mysqli_query($link, $query); 
    return $result;
}

$sql = 'SELECT * FROM `posts`';
mysqlQuery($sql, $link);

Index.php

<?php 
$database_host = 'localhost';
$database_username = 'root';
$database_password = 'root';
$database_name = 'db_name';
?>

<?php
include "config.php";
$link = mysqli_connect($database_host, $database_username, $database_password,$database_name);
if (mysqli_connect_errno())
    die('Could not connect: ' . mysqli_connect_error());
?>

<?php
function mysqlQuery($query) {
    $result = mysqli_query($link,$query); 
    return $result;
}
?>

    <?php
    include "header.php";
    include "function.php";
    $sql         =  "SELECT * FROM `posts`";
    mysqlQuery($sql);
    ?>

function mysqlQuery($query, $link) {
                          // ^ this one also
    $result = mysqli_query($link, $query); 
    return $result;
}

$sql = 'SELECT * FROM `posts`';
mysqlQuery($sql, $link);

---

是否真的有必要将测试用例分为四个独立的部分？查询之后，您必须

获取结果并
打印它们。但错误与范围有关。为什么要否决+1、依赖注入比使用
global
@DanFromGermany要好。是的，基于OP目前的情况，这种方式似乎还可以