mysql - 如何在mysql中的同一个表上执行内连接

Question

我在mysql中有一个名为sla的表，我需要获得与特定交换机相关的唯一交换机和port_no。我完全不知道哪个加入会对我有帮助。

+-------------------------+---------+
| switch                  | port_no |
+-------------------------+---------+
| 00:00:00:00:00:00:00:02 | 3       |
| 00:00:00:00:00:00:00:01 | 2       |
| 00:00:00:00:00:00:00:01 | 1       |
| 00:00:00:00:00:00:00:02 | 1       |
| 00:00:00:00:00:00:00:04 | 2       |

预期输出

+-------------------------+---------+
| switch                  | port_no |
+-------------------------+---------+
| 00:00:00:00:00:00:00:02 | 3,1     |
| 00:00:00:00:00:00:00:01 | 2,1     |
| 00:00:00:00:00:00:00:04 | 2       |

Answer 1

我通过使用 GROUP_CONCAT 函数得到了预期的输出。

select switch,GROUP_CONCAT(port_no) from sla group by switch;