Mysql 我们能做到这一点吗？如果是的话，那么SQL查询将为相同的问题提供什么

我有一个表，其中包含以下类型的数据：

+---------+------+--------+
| market  | type | amount |
+---------+------+--------+
| LTCBTC  | SELL |   0.15 |
| XMRBTC  | BUY  |  0.005 |
| DASHBTC | BUY  |  0.002 |
| ADABTC  | BUY  |      7 |
| IOTABTC | BUY  |      1 |
| LTCBTC  | BUY  |   0.17 |
| XRPBTC  | BUY  |     12 |
| ETHBTC  | BUY  |   0.03 |
| BCCBTC  | BUY  |  0.005 |
| ETHBTC  | SELL |  0.124 |
| LTCBTC  | BUY  |   0.02 |
| XMRBTC  | BUY  |  0.004 |
| DASHBTC | BUY  |  0.002 |
| ADABTC  | BUY  |      6 |
| IOTABTC | BUY  |      1 |
| XRPBTC  | BUY  |     10 |
| BCCBTC  | BUY  |  0.004 |
| ETHBTC  | BUY  |  0.025 |
| XMRBTC  | BUY  |  0.006 |
| DASHBTC | BUY  |  0.002 |
| LTCBTC  | BUY  |   0.02 |
| ETHBTC  | SELL |  0.026 |
| ETHBTC  | SELL |  0.004 |
| BCCBTC  | SELL |  0.005 |
| XRPBTC  | SELL |     14 |
+---------+------+--------+

这是我到今天为止购买或出售的硬币对的信息。我想找到每对硬币的确切数量

因此，基本上我希望得到以下回应：

+---------+------+----------------------+
| market  | type | sum(amount)          |
+---------+------+----------------------+
| ADABTC  | BUY  |                   13 |
| BCCBTC  | BUY  |        0.00400000019 |
| DASHBTC | BUY  | 0.006000000284984708 |
| ETHBTC  | BUY  |         -0.098999999 |
| IOTABTC | BUY  |                    2 |
| LTCBTC  | BUY  |         0.0599999949 |
| XMRBTC  | BUY  |  0.01500000013038516 |
| XRPBTC  | BUY  |                    8 |
+---------+------+----------------------+

有人能帮我查询一下吗

谢谢

我想简单的案例和分组应该有用

select market,
       sum(case when type = 'sell' then -amount
                when type = 'buy' then amount end)
from data
group by market

---

转变的逻辑是什么？你尝试过什么？说真的，这闻起来像是家庭作业，而你自己却没有表现出一点努力。选择。。。。。金额。。。其中type='BUY'按市场分组，type应该做一些小动作，如果summantium值小于0？ethbtcac实际上，我正在做一个小项目，我需要它，因为我很难理解这个查询。Ulricheckhardt的判断能力很强，它似乎适用于整数，但以DASHBTC为例。它的0.002+0.002+0.002=0.006000000284984708谢谢@Radim。这有帮助