PostgreSQL 查询帮助：如何检查多个列的值是不是同时增加/减少
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【中文标题】PostgreSQL 查询帮助：如何检查多个列的值是不是同时增加/减少【英文标题】：PostgreSQL query help: How to check if multiple columns are increasing/decreasing in value at the same timePostgreSQL 查询帮助：如何检查多个列的值是否同时增加/减少 【发布时间】：2020-05-24 07:22:54 【问题描述】：我有一个类似于下面的结果表：
如何查询随着时间的推移在 latest_price 和sentiment_change 中都在增加的代码。例如，您可以看到 AMSC 在 latest_price 和 mood_change 中都有所增加。我正在使用 postgresql 感谢您的帮助
"created_at" "ticker" "title" "latest_price" "sentiment_change"
"2020-05-24 06:41:40.948862" "AMSC" "American Superconductor Corporation" "6.66" "5.56"
"2020-05-24 06:42:02.987018" "AMSC" "American Superconductor Corporation" "7.66" "6.56"
"2020-05-24 07:59:08.014871" "AMSC" "American Superconductor Corporation" "8.66" "7.27"
"2020-05-24 08:00:23.406509" "AMSC" "American Superconductor Corporation" "9.66" "8.27"
"2020-05-24 08:04:02.881144" "AMSC" "American Superconductor Corporation" "10.66" "9.27"
"2020-05-24 06:41:51.797114" "AUPH" "Aurinia Pharmaceuticals Inc." "16.24" "-0.37"
"2020-05-24 06:41:52.768141" "CGC" "Canopy Growth Corporation " "19.42" "-0.89"
"2020-05-24 06:42:06.947722" "COF" "Capital One Financial Corp." "60.21" "9.19"
"2020-05-24 07:58:49.696729" "CNC" "Centene Corp." "64.84" "0.0"
"2020-05-24 08:00:05.909404" "CNC" "Centene Corp." "64.84" "0.0"
【问题讨论】：
【参考方案1】：我在这里为此创建了一个 db-fiddle：https://www.db-fiddle.com/f/37qeZWoFpVLkJLqN16TirX/0
如果您的 PostgreSQL 版本支持 LAG，您可以使用下面的查询开始。增加的部分我做了，减少的你可以做。
然后，您可以计算latest_price 或sentiment_change 相对于您的观察次数增加/减少的次数；如果高于/低于某个阈值，则确定您的行动方案。
SELECT
created_at,
ticker,
latest_price,
sentiment_change,
LAG(latest_price,1) OVER (
PARTITION BY ticker
ORDER BY created_at) AS previous_price,
CASE WHEN latest_price >= LAG(latest_price, 1) OVER (
PARTITION BY ticker
ORDER BY created_at)
THEN 1 ELSE 0 END AS increased_price_flag,
LAG(sentiment_change,1) OVER (
PARTITION BY ticker
ORDER BY created_at) AS previous_sentiment_change,
CASE WHEN sentiment_change >= LAG(sentiment_change, 1) OVER (
PARTITION BY ticker
ORDER BY created_at)
THEN 1 ELSE 0 END AS increased_sentiment_change_flag
FROM results
ORDER BY ticker, created_at;
结果：
| created_at | ticker | latest_price | sentiment_change | previous_price | increased_price_flag | previous_sentiment_change | increased_sentiment_change_flag |
| ------------------------ | ------ | ------------ | ---------------- | -------------- | -------------------- | ------------------------- | ------------------------------- |
| 2020-05-24T06:41:40.948Z | AMSC | 6.66 | 5.56 | | 0 | | 0 |
| 2020-05-24T06:42:02.987Z | AMSC | 7.66 | 6.56 | 6.66 | 1 | 5.56 | 1 |
| 2020-05-24T07:59:08.014Z | AMSC | 8.66 | 7.27 | 7.66 | 1 | 6.56 | 1 |
| 2020-05-24T08:00:23.406Z | AMSC | 9.66 | 8.27 | 8.66 | 1 | 7.27 | 1 |
| 2020-05-24T08:04:02.881Z | AMSC | 10.66 | 9.27 | 9.66 | 1 | 8.27 | 1 |
| 2020-05-24T06:41:51.797Z | AUPH | 16.24 | -0.37 | | 0 | | 0 |
| 2020-05-24T06:41:52.768Z | CGC | 19.42 | -0.89 | | 0 | | 0 |
| 2020-05-24T07:58:49.696Z | CNC | 64.84 | 0.00 | | 0 | | 0 |
| 2020-05-24T08:00:05.909Z | CNC | 64.84 | 0.00 | 64.84 | 1 | 0.00 | 1 |
| 2020-05-24T06:42:06.947Z | COF | 60.21 | 9.19 | | 0 | | 0 |
【讨论】：
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