MYSQL - 两列中的 WHERE 值

Question

我有一张这样的 table :

id | node_source    | node_destination | path
1  |        1       |       0          | {"coordinates": [[-6.27400693507...
2  |        0       |       1          | {"coordinates": [[-6.24568104953...
3  |        1       |       2          | {"coordinates": [[-6.24568104953...
4  |        2       |       1          | {"coordinates": [[-6.27230059993...

我想比较第 1 行和第 2 行、第 3 行和第 4 行之间的 node_source 和 node_destionation 的值。

如果 node_source in row 1 == node_destination in row 2 AND node_destination in row 1 == node_source in row 2 THEN display only first row (id=1)

如果 node_source in row 3 == node_destination in row 4 AND node_destination in row 3 == node_source in row 4 THEN display only third row (id=3)

最终输出如下:

id | node_source    | node_destination | path
1  |        1       |       0          | {"coordinates": [[-6.27400693507...
3  |        1       |       2          | {"coordinates": [[-6.24568104953...

这是我的代码(但不起作用):

SELECT * FROM graph t1 
    WHERE NOT EXISTS(SELECT * FROM graph t2 
                        WHERE t2.node_source = t1.node_destination AND t2.node_destination = t1.node_source
                    )

帮助。 谢谢。

Answer 1

我想你想要这个:

SELECT g.*
FROM graph g
WHERE g.node_source <= g.node_destination
UNION ALL
SELECT g.*
FROM graph g
WHERE g.node_source > g.node_destination AND
      NOT EXISTS (SELECT 1
                  FROM graph g2
                  WHERE g2.node_source = g.node_destination AND g2.node_destination = g.node_source
                 );

这将选择每对边中的一个边。