Sql r重复。对于OP所示的结构类似的表，修改字符串操作是不合适的。我将在几个小时后作出答复。希望问题到那时还没有结束，希望期望的输出到那时更具说服力。谢谢你，Yunnosch，我最终加入了另外两个表，使用了你的代码和@DinoCoderSaurus建议的合并函

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r重复。对于OP所示的结构类似的表，修改字符串操作是不合适的。我将在几个小时后作出答复。希望问题到那时还没有结束，希望期望的输出到那时更具说服力。谢谢你，Yunnosch，我最终加入了另外两个表，使用了你的代码和@DinoCoderSaurus建议的合并函数，从我的最终结果中得到了我想要的结果。为你的帮助干杯。

+------------------+----------+------------------+---------+------------------+---------+------------------+---------+------------------+---------+
| starting_item_id | quantity | starting_item_id | item_id | starting_item_id | item_id | starting_item_id | item_id | starting_item_id | item_id |
+------------------+----------+------------------+---------+------------------+---------+------------------+---------+------------------+---------+
|                1 |        1 |                1 |       4 |                  |         |                  |         |                  |         |
+------------------+----------+------------------+---------+------------------+---------+------------------+---------+------------------+---------+
|                2 |        1 |                  |         | 2                | 7       |                  |         |                  |         |
+------------------+----------+------------------+---------+------------------+---------+------------------+---------+------------------+---------+
|                3 |        1 |                  |         |                  |         | 3                | 30      |                  |         |
+------------------+----------+------------------+---------+------------------+---------+------------------+---------+------------------+---------+
|                4 |        1 |                  |         |                  |         |                  |         | 4                | 20      |
+------------------+----------+------------------+---------+------------------+---------+------------------+---------+------------------+---------+

+------------------+----------+------------------+---------+
| starting_item_id | quantity | starting_item_id | item_id |
+------------------+----------+------------------+---------+
|                1 |        1 |                1 |       4 |
+------------------+----------+------------------+---------+
|                2 |        1 |                2 |       7 |
+------------------+----------+------------------+---------+
|                3 |        1 |                3 |      30 |
+------------------+----------+------------------+---------+
|                4 |        1 |                4 |      20 |
+------------------+----------+------------------+---------+

starting_item_id  quantity    starting_item_id  item_id
----------------  ----------  ----------------  ----------
1                 1           1                 4
2                 1           2                 7
3                 1           3                 30
4                 1           4                 20

starting_item_id  quantity    item_id     kind
----------------  ----------  ----------  ----------
1                 1           4           weapon
2                 1           7           armor
3                 1           30          gear
4                 1           20          tool