輸出陣列的種方式：

function xiu_fetch_all($sql) {
	$conn = mysqli_connect(XIU_DB_HOST, XIU_DB_USER, XIU_DB_PASS, XIU_DB_NAME);
	if (!$conn) {
		exit('連線資料庫失敗');
	}
	$query = mysqli_query($conn, $sql);
	if (!$query) {
		//查詢失敗
		return false;
	}
	while ($row = mysqli_fetch_assoc($query)) {
		$result[] =
 
 $row;
	}
	mysqli_free_result($query);
	mysqli_close($conn);
	
	return $result;
}
$all = xiu_fetch_all("select count(1) as num from posts ;");
//var_dump();
var_dump($all);
//json_encode();
$new_all = json_encod($all);
	//結果：array(1) {
  [0]=>array(1) {
    ["num"]=>string(1) "4"
  }
}
echo $new_all;
 
//[{"num":"4"}]
//print_r();輸出陣列
print_r($all);
//Array ( [0] => Array ( [num] => 4 ) )