Question

我正在尝试在php中进行双重查询，并且由于某种原因无法正常工作。

Basicall我想在我的表中更新一行，其中id为MAX，fb_id等于fbId参数。

这是我的代码：

  public function updatePages($fbId, $nr_page = NULL) {
        $db = Database::getInstance();
        $query = "UPDATE visits SET pages =".$nr_page." WHERE id = (SELECT maxvalue FROM (SELECT MAX(id) AS maxvalue FROM visits WHERE fb_id =".$fbId."))";
        if($db->query($query))
            return true;
        return false;
    }

Answer 1

您可以尝试这种方式SELECT最大ID并分配给id WHERE子句

$query = "UPDATE visits SET pages =".$nr_page." WHERE id = (SELECT MAX(id) AS maxvalue FROM visits WHERE fb_id =".$fbId." LIMIT 1)";

Answer 2

你需要两个级别吗？试试这个：

$query = "UPDATE visits SET pages =".$nr_page." WHERE id = (SELECT id FROM visits WHERE fb_id =".$fbId." ORDER BY id DESC LIMIT 1)";

Answer 3

我最终成功了，这是解决方案：

  $query = "UPDATE visits SET pages =".$nr_page." WHERE fb_id =".$fbId." ORDER BY id DESC LIMIT 1";

php UPDATE和SELECT在同一个查询中

3 个答案: