根据第二个查询中的时间对两个查询的结果进行排序[关闭]

Question

我需要按时间顺序获取结果，但是因为我在一段时间内使用 sql 查询进入另一个 sql 查询，所以我得到了由$arrID排序的结果

$req1==mysql_query("SELECT friendId FROM friends ");
while($res1=mysql_fetch_row($req1)) {
    $arrID = $res['friendId'];

    $req = mysql_query("SELECT * FROM posts WHERE postby=$arrID  ORDER BY posttime DESC ");
    while ($res = mysql_fetch_row($req)) {
        echo $res['bostby'];
        echo $res['postcontent'];
    }
}

结果是：

post 1 by 2 content aaaaaaaa  time: 11:60
post 2 by 2 content bbbbbbbb   time 11:59
post 3 by 2 content aaaaaaaa  time: 11:58
post 4 by 2 content bbbbbbbb   time 11:56
post 5 by 3 content aaaaaaaa  time: 11:61
post 6 by 3 content bbbbbbbb   time 11:60
post 7 by 3 content aaaaaaaa  time: 11:59
post 8 by 5 content bbbbbbbb   time 12:20
post 8 by 5 content bbbbbbbb   time 12:19

我需要按时间而不是按 id 排序结果

post 8 by 5 content bbbbbbbb   time 12:20
post 8 by 5 content bbbbbbbb   time 12:19
post 1 by 2 content aaaaaaaa  time: 11:60
post 6 by 3 content bbbbbbbb   time 11:60
post 2 by 2 content bbbbbbbb   time 11:59
post 7 by 3 content aaaaaaaa  time: 11:59

Answer 1

使用连接两个表的单个查询，而不是执行嵌套循环。

SELECT p.* FROM posts AS p
JOIN friends AS f ON p.postby = f.friendId
ORDER BY p.posttime DESC

从您的评论看来，您的第一个查询并不那么简单。但是你可以加入一个子查询。

SELECT p.* FROM posts AS p
JOIN (
    SELECT user_from AS friendId
    FROM friend_requests 
    WHERE user_to = $SessionID AND accepted = '1'
    UNION
    SELECT user_to AS friendId
    FROM friend_requests
    WHERE user_from = $SessionID AND accepted = '1'
) AS f ON p.postby = f.friendId
ORDER BY p.posttime DESC