How to fetch from MySql Database when using Include connection?

Question

I'm using include connection file to connect to the database. My challenge is how do I fetch from the database this is where am stuck.

include 'connection.php';

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

Answer 1

assume your connection.php contain

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

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

So the in your file, you're using include 'connection.php' to get the connection. By using include its act like single page now. Then you've to use it like below

  require_once 'connection.php';

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

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Explanation

when you add this include 'connection.php'; then whatever the data on parent(connection.php) file (ex: variable, Functions, etc ..) will come to child.

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Links to refer

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?