Question

我有这张桌子，名为奖励：

+----+------------+-----------+----------+-------------+
| id | product_id | sell_what | get_what | valid_until |
+----+------------+-----------+----------+-------------+
| 1  | 1001       | 10        | 10000    | 15 nov 2015 |
| 2  | 1002       | 7         | 12000    | 31 dec 2015 |
| 3  | 1003       | 12        | 100000   | 31 dec 2015 |
+----+------------+-----------+----------+-------------+

并且，我有这个名为user_earned的表：

+----+---------+------------+-----------+------------------+
| id | user_id | product_id | sell_what | transaction_date |
+----+---------+------------+-----------+------------------+
| 1  | 609     | 1003       | 1         | 2 Nov 2015       |
| 2  | 220     | 1001       | 12        | 3 Nov 2015       |
| 3  | 609     | 1003       | 1         | 20 Nov 2015      |
| 4  | 910     | 1001       | 2         | 21 Nov 2015      |
| 5  | 910     | 1001       | 3         | 21 Nov 2015      |
| 6  | 910     | 1001       | 8         | 22 Nov 2015      |
+----+---------+------------+-----------+------------------+

我也有此查询根据sell_what总结user_id号码：

SELECT user_id, product_id, 
SUM(sell_what) AS sold, 
MAX(transaction_date) AS transaction_date
FROM user_earned 
GROUP BY user_id, product_id

以及结果：

+---------+------------+-----------+------------------+
| user_id | product_id | sold      | transaction_date |
+---------+------------+-----------+------------------+
| 220     | 1001       | 12        | 3 Nov 2015       |
| 609     | 1003       | 2         | 20 Nov 2015      |
| 910     | 1001       | 13        | 22 Nov 2015      |
+---------+------------+-----------+------------------+

现在，问题是......如何将这个结果与表奖励结合起来，以便我得到这样的表：

+---------+------------+-----------+-------------------+
| user_id | product_id | sold      | remaining_balance |
+---------+------------+-----------+-------------------+
| 220     | 1001       | 12        | 2                 |
+---------+------------+-----------+-------------------+

用户609不可见，因为他只售出2件产品，而产品1003的最低奖励为12件。

用户910不可见，因为他最新的产品1001的transaction_date是2015年11月22日，而奖励仅在2015年11月15日之前有效。

如何将此条件应用于一个SQL语法？谢谢。

Answer 1

我想你想要这种要求吗？

select * ,
    (t.sold - r.sell_what) as remaining_balance
from reward as r
inner join (
    SELECT user_id, product_id, 
    SUM(sell_what) AS sold, 
    MAX(transaction_date) AS transaction_date
    FROM earned_incentive 
    GROUP BY user_id, product_id
    ) as t
    on r.product_id = t.product_id
WHERE 
    r.sell_what <= t.sold
    and t.transaction_date <= r.valid_until

检查SQL Fiddlesqlfiddle http://sqlfiddle.com/images/fiddle_transparent_small.png

基于SELECT的MySQL条件语法

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