如何从数组变量PHP获取指定列到动态变量

I have a table in MYSQL called guest. There are 3 columns in the guest table GuestId, Name, Phone. I want to select all records from the guest table and put it into array variables, then I just want to get the phone value from array variables using (for) loop. I have tried using (for) loop then inside the loop I use :

$phone = $row[phone]; 

but the result I get is just the value phone of the first record. How to make the phone variables take the phone value from each record in every looping?

Thank you.

Use

$phones = array_column($arr, 'Phone');

Check http://php.net/manual/en/function.array-column.php

<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";


$conn = new mysqli($servername, $username, $password, $dbname);

if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
} 

$sql = "SELECT GuestId, Name, Phone FROM guest";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    // output data of each row
    while($row = $result->fetch_assoc()) {
        echo "Phone: " . $row["Phone"]. "<br>";
    }
} else {
    echo "0 results";
}
$conn->close();
?>