反向数据的MySQL查询

我对MySQL查询有问题。我有如下数据：

transaction_type | currency_from | currency_to |
------------------------------------------------
swap             | USD           | IDR         |
swap             | IDR           | USD         |
forward          | GBP           | USD         |
forward          | USD           | GBP         |
forward          | JPY           | EUR         |
forward          | EUR           | JPY         |
spot             | USD           | EUR         |
spot             | EUR           | USD         |

transaction_type | currency_from | currency_to |
------------------------------------------------
swap             | USD           | IDR         |
forward          | GBP           | USD         |
forward          | JPY           | EUR         |
spot             | USD           | EUR         |

是否可以让输出看起来像这样：

transaction_type | currency_from | currency_to |
------------------------------------------------
swap             | USD           | IDR         |
swap             | IDR           | USD         |
forward          | GBP           | USD         |
forward          | USD           | GBP         |
forward          | JPY           | EUR         |
forward          | EUR           | JPY         |
spot             | USD           | EUR         |
spot             | EUR           | USD         |

transaction_type | currency_from | currency_to |
------------------------------------------------
swap             | USD           | IDR         |
forward          | GBP           | USD         |
forward          | JPY           | EUR         |
spot             | USD           | EUR         |

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如上所述，每笔交易都会有反向交易，掉期美元-IDR，也会有掉期IDR-USD远期GBP-USD也会有远期美元-GBP，现货也是如此。我尝试了很多方法，但仍然没有成功。有人能帮忙吗？谢谢你

您可以执行以下操作

SELECT t1.*
FROM tblTransaction AS t1 INNER JOIN tblTransaction AS t2
ON (
    t1.transaction_type = t2.transaction_type AND 
    t1.currency_from = t2.currency_to AND
    t1.currency_to = t2.currency_from AND
    t1.currency_from > t2.currency_from
)

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哇！谢谢你的快速回复。。它起作用了。。你救了我一天。。谢谢……）