这是一个创建于 2200 天前的主题，其中的信息可能已经有所发展或是发生改变。
在 https://segmentfault.com/ 上问了个问题，结果并没有人理。
12 条回复 • 2018-12-21 16:41:26 +08:00
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1
cyhulk 2018-12-20 10:58:01 +08:00
mysql 可以增加局部变量，select 局部变量做操作就行了
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wqzjk393 2018-12-20 10:58:02 +08:00
对第二张表 group by id，然后 sum 一下总的消费金额 生成一个临时表 3。剩余金额就是 select (表 1.总金额-表 3.消费金额) from 表 1 join 表 3。不知道是不是这个意思
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CRVV 2018-12-20 11:35:52 +08:00  1
WITH data AS (
SELECT created_at, id AS card_id, total, total AS amount FROM card UNION ALL SELECT transaction.created_at, card_id, card.total, -transaction.total FROM transaction INNER JOIN card ON card_id = card.id) SELECT created_at, card_id, total, sum(amount) OVER (PARTITION BY card_id ORDER BY created_at) FROM data; 重点是 window function，sum(amount) OVER (PARTITION BY card_id ORDER BY created_at) |
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6
suiterchik 2018-12-20 13:51:56 +08:00
都上窗函数了为啥不
sum(amount) over( partition by card_id order by created_at rows between unbounded preceding and current row ) 这个可以计算截至到当前行的支付总额 |
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7
ziding 2018-12-20 14:02:42 +08:00
这种需求建议在业务层处理，窗口函数用起来爽，等到后面加需求的时候，慢慢慢慢的性能就被脱下来了。
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8
suiterchik 2018-12-20 14:03:40 +08:00
@CRVV 你这个 sql 不约束行号不行吧，OVER (PARTITION BY card_id ORDER BY created_at) 这个窗，card_id 相同的记录返回的值都是一样的
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9
CRVV 2018-12-20 14:58:16 +08:00
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suiterchik 2018-12-20 17:44:34 +08:00 via Android
@CRVV 默认的 rows between 是 rows between unbounded preceding and unbounded following，楼主的需求是求当前时间的累积，显然要约束在 current row
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12
zhangolve OP WITH data AS (
SELECT created_at, id AS card_id, total, total AS remaining_total FROM prepay_card UNION ALL SELECT pct.created_at, pct.prepay_card_id AS card_id, pc.total, -pct.total AS remaining_total FROM prepay_card_transaction pct INNER JOIN prepay_card pc ON pct.prepay_card_id = pc.id ) SELECT created_at, card_id, total,sum(remaining_total) OVER (PARTITION BY card_id ORDER BY created_at) AS remaining_total_all FROM data ORDER BY card_id, created_at ; 补充一下我根据 @CRVV 改写的 sql |
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