echo SELECT QUERY mysqli

Question

ここに私のコードがあります。「ok」が表示されないエコーを実行します。どうすればいいですか？

<?php 

    $username = "root"; 
    $password = ""; 
    $db = "db2"; 

    // Create connection 

    $conn = mysqli_connect("localhost", $username, $password, $db); 

    if (!@$conn) { 
    die ("Unable to Connect!"); 
    } 
    else { 
     echo "Connected!"; 
    } 

    $sql = "SELECT 'food', 'calorie' FROM 'food' ORDER BY 'id'"; 
    $query = mysqli_query($conn, $sql); 
    if ($query) { 
    echo "ok"; 
    } 
    ?> 

Answer 1

<?php 

$username = "root"; 
$password = ""; 
$db = "db2"; 

// Create connection 

    $conn = mysqli_connect("localhost", $username, $password, $db); 

if (!@$conn) { 
    die ("Unable to Connect!"); 
    } 
else { 
    echo "Connected!"; 
} 

$sql = "SELECT food, calorie FROM food ORDER BY id"; 
$query = mysqli_query($conn, $sql); 
    if ($query) { 
    echo "ok"; 
    } 
    ?>