一个带有奇怪结果的PHP include（）函数

Question

I start learning PHP quite recently,and I met a frustrating problem in which the code seems good, but it just won't work,even the one who teach me don't know what cause it. Below I'll paste my code to you.

<?php
header("content-type: text/html; charset = UTF-8");
$con = new mysqli();
$con -> connect("localhost", "root" ,"");
$con -> select_db("test_db");
$con -> query("set names UTF8");
$query = $con -> query("SELECT * FROM TITLES LIMIT 0,2");
$num = $query -> num_rows;
for ($i=1 ; $i <= $num; $i++) 
{ 
    $result = $query -> fetch_array();
    echo "<table style ='float: left'>";
    echo "<tr><th>".$result["TITLE"]."</th><tr>";
    echo "<tr><td>";
    include("$i.php");
    echo "</td></tr>";
    echo "</table>";
}
?>

And the result turn to be this:

By the way,I'm using XAMPP 7.0.1 in MAC.

<?php
header("content-tupe: text/html; charset = UTF-8");
$con = new mysqli();
$con -> connect("localhost", "root" ,"");
$con -> select_db("test_db");
$con -> query("set names UTF8");
$query = $con -> query("SELECT * FROM PHP_MANUAL LIMIT 0,6");
?>
<ul>
<?php
  while ($result = $query -> fetch_array()) 
  {
      echo "<li>".$result["CONTENT"]."</li>";
  }
?>
</ul>

Answer 1

When you include a file in another PHP file all variables in the included file will be active and accessible for manipulation.

In your case you are using $query and $result variables which override the one you started. So the $query of TITLES has been changed and therefore even if you want to use unset() it won't work.

Example: Basic include example

vars.php

<?php

$color = 'green';
$fruit = 'apple';

?>

test.php

$color = 'yellow';
$fruit = 'banana';

echo "A $color $fruit"; // A yellow banana

include 'vars.php';

echo "A $color $fruit"; // A green apple

?>

Source: http://php.net/manual/en/function.include.php

Also the $con variable you may want to put in a separated PHP file and included once. Read more about PHP include:

http://php.net/manual/en/function.include-once.php