闭合表（移动子树）

Question

嗨，我的数据库设计为

+-------------+--------------+-------+
| referral_id | referrent_id | level |
+-------------+--------------+-------+

在我的数据库中，我有一排这样的数据：

+---+---+---+
| 1 | 1 | 0 |
+---+---+---+
| 1 | 2 | 1 |
+---+---+---+
| 1 | 3 | 1 |
+---+---+---+
| 1 | 4 | 1 |
+---+---+---+
| 2 | 2 | 0 |
+---+---+---+
| 3 | 3 | 0 |
+---+---+---+
| 4 | 4 | 0 |
+---+---+---+

基本上树是

  / 2
1 - 3
  \ 4

我正在尝试将3降低到2以下

  / 2 - 3
1 - 4

我的实现：

public function changeReferrer(Member $newReferrer) {
        $oldReferrer = $this->getReferrer(1); // this retrieves the ancestor one level up
        DB::select('DELETE a FROM Referrer_Referent AS a
                    JOIN Referrer_Referent as d ON a.referent_id = d.referent_id
                    LEFT JOIN Referrer_Referent AS x
                    ON x.referrer_id = d.referrer_id AND x.referent_id = a.referrer_id
                    WHERE d.referrer_id = '.$oldReferrer->id.'
                    AND x.referrer_id IS NULL');

        DB::select('INSERT into Referrer_Referent (referrer_id, referent_id, level)
                    SELECT supertree.referrer_id, subtree.referent_id, supertree.level + subtree.level + 1
                    FROM Referrer_Referent as supertree JOIN Referrer_Referent as subtree
                    WHERE subtree.referrer_id = '.$oldReferrer->id.'
                    AND supertree.referent_id = '.$newReferrer->id);
    }

所以我将函数称为$user3->changeReferrer($user2);，但出现这些错误：

  

违反完整性约束：1062键“ PRIMARY”的重复条目“ 1-1”（SQL：插入Referrer_Referent（referrer_id，referent_id，级别）SELECT SELECT supertree.referrer_id，subtree.referent_id，supertree.level + subtree.level + 1 FROM Referrer_Referent作为父树JOIN Referrer_Referent作为子树WHERE subtree.referrer_id = 1 AND supertree.referent_id = 2）

将此blog作为参考。