要颠倒顺序（因此获取最后10个而不是前10个），请使用DESC而不是ASC

编辑

基于您的评论：

SELECT * FROM (
  SELECT * 
  FROM chat 
  WHERE (userID = $session AND toID = $friendID) 
    OR (userID = $friendID AND toID = $session)  
  ORDER BY id DESC
  LIMIT 10
) AS `table` ORDER by id ASC

如果你想要最后的10个，那么只需将ASC更改为DESC

SELECT * 
FROM 
chat 
WHERE 
(userID=$session AND toID=$friendID) 
OR 
(userID=$friendID AND toID=$session) 
ORDER BY id 
DESC
LIMIT 10

$con = mysqli_connect("localhost","my_user","my_password","my_db");
$limit = 10;                
$query = "SELECT * FROM  $table";
$resource = mysqli_query($con,$query);
$total_rows = mysqli_num_rows($resource);
$start = $total_rows-$limit;
$query_limit= $query." LIMIT $start,$limit";

首先我设定了限制

$limit = 10;

然后

$total_rows = mysqli_num_rows($resource);

在这里，我已经采取了受影响的行的总数。

$start = $total_rows-$limit;

然后从行数中减去限制以获取起始记录号

$query_limit= $query." LIMIT $start,$limit";

然后将限制添加到查询。有关限制的更多信息，请参阅此链接https://www.w3schools.com/php/php_mysql_select_limit.asp

首先从表中选择最后10个，然后按升序重新排序。

SELECT * FROM (SELECT * FROM table ORDER BY id DESC LIMIT 10) sub ORDER BY id ASC