Question

我这里有MySQL查询..

/***
 * An ugly self joining sql.
 * We want the parent's name so we have to join with the same table
 *    joining on child_row.parent_id = parent_row.id
 * Don't remove the LIMIT from this... it might be bad.
 */
$sql = 'SELECT cNode.*, pNode.name as parent_name ';
$sql.= ' FROM t_nodes AS cNode LEFT JOIN t_nodes AS pNode ';
$sql.= ' ON cNode.parent_id = pNode.id ';
$sql.='  WHERE cNode.id = '.$id.' LIMIT 1';

有没有办法让这更优雅？

Answer 1

与SQL无关，只是为了提高PHP源代码的可读性：

$sql = "
    SELECT cNode.*, pNode.name as parent_name
    FROM t_nodes AS cNode LEFT JOIN t_nodes AS pNode
    ON cNode.parent_id = pNode.id
    WHERE cNode.id = $id LIMIT 1
";

Answer 2

我能想到的唯一合理的替代方案是获取父名称的相关子查询...

SELECT
  cNode.*,
  (SELECT name FROM t_nodes AS parent WHERE id = t_nodes.parent_id) AS parent_name
FROM
  t_nodes
WHERE
  cNode.id = $id
LIMIT 1

更简单的方法使这个SQL查询更好

2 个答案: