在SELECT语句中绑定排序属性

Question

对于带有排序顺序的SELECT查询，我准备这个语句：

$direction = 'DESC';
$project_id = 1;

$query = $this->connection->prepare('SELECT text FROM marker WHERE project_id = :project_id ORDER BY time :direction');
$query->bindValue(':project_id', $project_id, PDO::PARAM_INT);
$query->bindValue(':order', $direction, PDO::PARAM_STR);
$success = $query->execute();

但它失败了。所以我准备这个声明：

$query = $this->connection->prepare('SELECT text FROM marker WHERE project_id = :project_id ORDER BY time '.$direction.'');
$query->bindValue(':project_id', $project_id, PDO::PARAM_INT);
$success = $query->execute();

它有效。

可以不绑定ORDER属性吗？ 如何正确绑定ORDER属性？

Answer 1

您可以使用case声明表达您想要的内容。这是一个相对简单的表达式：

order by (case when :order = 'DESC' then time end) DESC,
         time ASC