php - 使用包含连接时如何从 MySql 数据库中获取？

Question

我正在使用包含连接文件连接到数据库。我的挑战是如何从卡住的数据库中获取数据。

include 'connection.php';

$sql = 'SELECT * FROM country';
$results = mysqli_query($sql);

Answer 1

假设你的 connection.php 包含

  <?php
        $con = mysqli_connect("localhost","my_user","my_password","my_db");

        if (mysqli_connect_errno())
        {
              echo "Failed to connect to MySQL: " . mysqli_connect_error();
        }
  ?>

所以在您的文件中，您正在使用 include 'connection.php' 来获取连接。通过使用 include它现在就像单页一样。然后你必须像下面这样使用它

  require_once 'connection.php';

  $sql= 'SELECT * FROM country';
  $results = mysqli_query($con, $sql); # add connection string to query 

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解释

当您添加此 include 'connection.php'; 时，无论父级 (connection.php) 文件中的数据是什么(例如:变量、函数等 ..) 会传给 child 。

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引用链接

1. In PHP, how does include() exactly work?
2. Are PHP include paths relative to the file or the calling code?
3. include, include_once, require or require_once?