Php 大型mysql数据库上的Order by rand（）

由于这个mysql查询，我的站点的速度非常慢

SELECT content.*,
       (SELECT content_views.views FROM content_views WHERE content_views.content = content.record_num) as views ,
       (SELECT images.filename FROM images WHERE images.record_num = content.thumbnail) AS thumbfile
FROM content WHERE enabled = 1  $filterAnd
ORDER BY RAND()
LIMIT $from,$max_results

我知道最好的方法就是这样使用它：

SELECT name
  FROM random AS r1 JOIN
       (SELECT CEIL(RAND() *
                     (SELECT MAX(id)
                        FROM random)) AS id)
        AS r2
 WHERE r1.id >= r2.id
 ORDER BY r1.id ASC
 LIMIT 1

但是我正在使用多个mysql表，我不知道如何像这样使用我的查询，有人能帮我吗

多谢各位

编辑：

我试过：

SELECT content.*,
       (SELECT content_views.views FROM content_views WHERE content_views.content = content.record_num) as views ,
       (SELECT images.filename FROM images WHERE images.record_num = content.thumbnail) AS thumbfile
FROM content AS r1 JOIN
     (SELECT (RAND() * (SELECT MAX(record_num) FROM content)) AS id) AS r2
WHERE r1.id >= r2.id
ORDER BY r1.id ASC
LIMIT 1

---

但现在我得到了错误：未知表“content”

此代码从content表中随机选择一行

现在，您需要将此查询视为一个名为randomTable字段的表，就像在content table中一样。现在你可以从中选择，加入它，做你需要的一切。注意$filter，我用了两次。仅当$filter包含与内容表相关的条件时，此选项才起作用。

您已为表内容指定了名为r1的别名。然后，您需要使用该别名来引用该特定表：

SELECT r1.*,
       (SELECT cv.views
        FROM content_views cv
        WHERE cv.content = r1.record_num
       ) as views,
       (SELECT i.filename
        FROM images i
        WHERE i.record_num = r1.thumbnail
       ) AS thumbfile
FROM content r1 JOIN
     (SELECT RAND() * (SELECT MAX(record_num) FROM content) AS id
     ) r2
WHERE r1.id >= r2.id
ORDER BY r1.id ASC
LIMIT 1

---

此版本中的许多表都有表别名。

到目前为止，大多数建议都采用无孔的自动增量id。如果这不适用，请参阅该解决方案，再加上7个

SELECT r1.*,
       (SELECT cv.views
        FROM content_views cv
        WHERE cv.content = r1.record_num
       ) as views,
       (SELECT i.filename
        FROM images i
        WHERE i.record_num = r1.thumbnail
       ) AS thumbfile
FROM content r1 JOIN
     (SELECT RAND() * (SELECT MAX(record_num) FROM content) AS id
     ) r2
WHERE r1.id >= r2.id
ORDER BY r1.id ASC
LIMIT 1