<?php
$con=mysqli_connect("localhost","my_user","my_password","my_db");
// Check connection
if (mysqli_connect_errno($con))
{
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}

$sql="SELECT Lastname,Age FROM Persons ORDER BY Lastname";
$result=mysqli_query($con,$sql);

// Fetch all
mysqli_fetch_all($result,MYSQLI_ASSOC);

// Free result set
mysqli_free_result($result);

mysqli_close($con);
?>