備份：關於mysqi的一些對比

mysqli->fetch_all 後面有三個參數，參數對比的返回結果如下：

MYSQLI_BOTH:

    [0] => Array
        (
            [0] => 1011
            [ID] => 1011
            [1] => Kudus
            [Name] => Kudus
            [2] => IDN
            [CountryCode] => IDN
            [3] => Central Java
            [District] => Central Java
            [4] => 95300
            [Population] => 95300
        )

MYSQLI_NUM:

    [0] => Array
        (
            [0] => 1011
            [1] => Kudus
            [2] => IDN
            [3] => Central Java
            [4] => 95300
        )

MYSQLI_ASSOC:

   [0] => Array

        (
            [ID] => 1011
            [Name] => Kudus
            [CountryCode] => IDN
            [District] => Central Java
            [Population] => 95300
        )

mysqli->fetch_array: 返回一條數組記錄，可以帶上面的參數；

fetch_assoc 返回的結果等同於 fetch_array（MYSQLI_ASSOC）; $row['name']

fetch_row 返回的結果等同於fetch_array(MYSQLI_NUM) $row[0]

fetch_field_direct 返回字段的元數據信息。例如長度，類型等等信息；

fetch_object 返回一個對象操作；前面都是在使用下標操作 $row->name;

如果查詢不到數據：

fetch_all 返回的是一個數組對象；

tetch_object，fetch_row等返回的是NULL對象，這點是有很大的不同的;