PHP連接數據庫並讀取數據打印

<?php

$link = mysqli_connect("localhost","root","root") or die("Connect error");
if($link){
    echo "Connect success<br>";
    mysqli_select_db($link, "world");
    $sql = "select * from city";
    $result = mysqli_query($link, $sql);
    $rows = mysqli_num_rows($result);
    $cols = mysqli_num_fields($result);
    echo "rows are ".$rows.", cols are ".$cols."<br>";
    echo "<table border='1' align='center' width='80%'>";
    echo "<caption>City info</caption>";
    echo "<th>ID</th><th>Name</th><th>CountryCode</th><th>District</th><th>Population</th>";
    while ($row=mysqli_fetch_row($result)){
        echo "<tr align='center'>";
        foreach ($row as $data){
            echo "<td>".$data."</td>";
        }
        echo "</tr>";
    }
    echo "</table>";
}else {
    echo "Connect error";
}
?>