php - MySQL Query 适用于 SQL 但不适用于 PHP

Question

我有一个名为 HWC 的表，我想获得一个随机行，我的数据库有大约 10k 个条目，而我之前使用的方法太慢了。

这是我的查询：

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

这是我在 PHP 中遇到的错误：

Error Number: 1064

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '* FROM HWC AS r1 JOIN (SELECT (RAND() * (SELECT MAX(id) FROM HWC)) AS id) A' at line 2

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

我的模型的完整 PHP 代码：

function random()
{
$query = "SELECT *
FROM HWC AS r1 JOIN
   (SELECT (RAND() *
                 (SELECT MAX(id)
                    FROM HWC)) AS id)
    AS r2 WHERE r1.id >= r2.id
ORDER BY r1.id ASC
LIMIT 1";
$result = $this->db->get($query);

return $result->result_array();
}

Answer 1

我的 get() 应该是一个 query(); 现在工作完美而快速。

Answer 2

去掉第二个刻度SELECT：

SELECT * FROM (SELECT * FROM HWC ...