Question

我的delas和curencies表格看起来像这样

curecnies
id,code

pairs (the available pairs of curencies )
id  to_sell to_buy

deals 
id
user_id
pair_id
amount_to_sell
amount_to_buy

所以我需要获得所有可以执行的匹配优惠，但我无法获得唯一的匹配。

这是我的SQL查询

select *
from deals as d1
join deals d2
    on d1.sell_amount = d2.buy_amount and d1.buy_amount = d2.sell_amount

1|2|1|1000|3000|2|1|2|3000|1000
2|1|2|3000|1000|1|2|1|1000|3000

Answer 1

您可以尝试使用最少/最好的技巧：

SELECT t1.*, t2.*
FROM
(
    SELECT DISTINCT
        LEAST(d1.id, d2.id) AS d1_id,
        GREATEST(d1.id, d2.id) AS d2_id
    FROM deals AS d1
    INNER JOIN deals d2
        ON d1.sell_amount = d2.buy_amount AND
           d1.buy_amount = d2.sell_amount
) d
INNER JOIN deals t1
    ON d.d1_id = t1.id
INNER JOIN deals t2
    ON d.d2_id = t2.id;

这里的基本思想是标记为d的子查询使用最小/最大技巧找到一对匹配的交易ID。然后，我们再次加入deals表两次，以获取该交易对中每个成员的完整信息。

连接结果中的唯一行

1 个答案: