<?php
$sql="SELECT * FROM books";
$result = $mysqli->query($sql);
//查詢結果迴圈給定陣列
while($row[]=$result->fetch_array(MYSQLI_ASSOC)){
$str =$row['書籍名稱'];
}

?>

$row = $result->fetch_array(MYSQLI_NUM);
$row = $result->fetch_array(MYSQLI_ASSOC);
$row = $result->fetch_array(MYSQLI_BOTH);
MYSQLI_ASSOC：文字欄位
MYSQLI_NUM：數字欄位
MYSQLI_BOTH：兩者都有