将MySQL查询转换为codeigniter中的活动记录

Question

如何将以下内容转换为适当的codeigniter活动记录语法。

function postsInterest($user_id)
{
    $query = $this->db->query("
    SELECT b.*,
    users.country,
    users.company,
    users.pic_small,
    users.subscription,
    COUNT(leads.user_id) AS leads
    FROM trading AS u
    INNER JOIN trading AS b
    LEFT JOIN users ON users.user_id = b.user_id
    LEFT JOIN leads ON b.trade_id = leads.trade_id
    WHERE u.stock_type = b.stock_type
    AND u.buying_selling != b.buying_selling
    AND u.bond = b.bond
    AND u.user_id = $user_id
    AND b.user_id != $user_id
    AND u.timestamp > unix_timestamp(now() - interval 120 DAY)
    AND b.timestamp > unix_timestamp(now() - interval 120 DAY)
    GROUP BY b.trade_id
    ORDER BY b.timestamp DESC");
    if ($query->num_rows() > 0) {
        return $query->result_array();
    } else {
        return false;
    }
}

上面的代码可以快速解决问题，但希望使其与其余查询保持一致，以便我可以使用分页库。

Answer 1

我不确定该查询是否会正常工作。 INNER JOIN trading AS b但没有指定 INNER JOIN trading AS b 条件，尽管所需的谓词在where子句中。 这些是“加入条件”

WHERE u.stock_type = b.stock_type
    AND u.buying_selling != b.buying_selling
    AND u.bond = b.bond

在每一个表中，边上都有一张桌子u ，另一边是一张桌子b 。 使用显式联接语法时，应将所有此类谓词移至联接上。

我相信您将获得更多成功，将其转换为codeigniter语法：

SELECT
      b.*
    , users.country
    , users.company
    , users.pic_small
    , users.subscription
    , COUNT(leads.user_id) AS leads
FROM trading AS u
INNER JOIN trading AS b ON u.stock_type = b.stock_type
      AND u.buying_selling != b.buying_selling
      AND u.bond = b.bond
LEFT JOIN users ON users.user_id = b.user_id
LEFT JOIN leads ON b.trade_id = leads.trade_id
WHERE u.user_id = @user_id
AND b.user_id != @user_id
AND u.timestamp > unix_timestamp(now() - interval 120 DAY)
AND b.timestamp > unix_timestamp(now() - interval 120 DAY)
GROUP BY
      b.trade_id
ORDER BY
      b.timestamp DESC

请注意，您依赖于MySQL对分组查询的非标准支持，并且如果sql_mode由我们的查询更改为only_full_group_将会失败。 在MySQL 5.7.2中，默认值为only_full_group_by