MySQL查询以获取每个月数据的平均值数组
[英]MySQL query to get array of averages of each month's data
问题描述
I have a table named historical_currencies_rate where I have saved last 8 years currency rate of some known currencies. 
我有一个名为historical_currencies_rate的表，在其中保存了过去8年中某些已知货币的汇率。 eg (EUR-USD). 例如（EUR-USD）。 Table looks like this 桌子看起来像这样
+---------------------------+---------------+------------+
| rate_date | currency_pair | rate |
+---------------------------+---------------+------------+
| 2006-01-01 | EUR-USD | 1.1797 |
| 2006-02-01 | EUR-USD | 1.1826 |
| 2006-03-01 | EUR-USD | 1.1875 |
| 2006-04-01 | EUR-USD | 1.2083 |
| 2006-05-01 | EUR-USD | 1.2088 |
| 2006-06-01 | EUR-USD | 1.2093 |
| 2006-07-01 | EUR-USD | 1.2093 |
| 2006-08-01 | EUR-USD | 1.2093 |
| 2006-01-01 | JPY-USD | 0.01275 |
| 2006-02-01 | JPY-USD | 0.01275 |
| 2006-03-01 | JPY-USD | 0.01275 |
| 2006-04-01 | JPY-USD | 0.01275 |
| 2006-05-01 | JPY-USD | 0.01275 |
| 2006-06-01 | JPY-USD | 0.01275 |
| 2006-07-01 | JPY-USD | 0.01275 |
| 2006-08-01 | JPY-USD | 0.01275 |
| 2006-01-01 | GBP-USD | 1.559 |
| 2006-02-01 | GBP-USD | 1.559 |
| 2006-03-01 | GBP-USD | 1.559 |
| 2006-04-01 | GBP-USD | 1.559 |
| 2006-05-01 | GBP-USD | 1.559 |
| 2006-06-01 | GBP-USD | 1.559 |
| 2006-07-01 | GBP-USD | 1.559 |
| 2006-08-01 | GBP-USD | 1.559 |
| 2006-01-01 | AUD-USD | 1.0515 |
| 2006-02-01 | AUD-USD | 1.0515 |
| 2006-03-01 | AUD-USD | 1.0515 |
| 2006-04-01 | AUD-USD | 1.0515 |
| 2006-05-01 | AUD-USD | 1.0515 |
| 2006-06-01 | AUD-USD | 1.0515 |
| 2006-07-01 | AUD-USD | 1.0515 |
| 2006-08-01 | AUD-USD | 1.0515 |
| 2006-01-02 | EUR-USD | 1.2092 |
| 2006-02-02 | EUR-USD | 1.2066 |
| 2006-03-02 | EUR-USD | 1.2061 |
| 2006-04-02 | EUR-USD | 1.2061 |
| 2006-05-02 | EUR-USD | 1.2061 |
| 2006-06-02 | EUR-USD | 1.1981 |
| 2006-07-02 | EUR-USD | 1.1973 |
| 2006-08-02 | EUR-USD | 1.1948 |
+---------------------------+---- ----------+------------+
here I have shown you tha data of few currency upto 8 days and for year 2006 but i have a huge data of 18 currencies with 30 days data upto 2013. 在这里，我向您显示了直到2006年的8天之内的几种货币的数据，但是我有一个庞大的数据，其中包含了截至2013年的30天的18种货币的数据。
My query is that I want an array which contains the avg currency rate of a particular currency on monthly basis. 我的查询是我想要一个包含每月特定货币的平均货币汇率的数组。 for eg avg of EUR-USD in my example for the month of January is 1.19935 , JPY-USD is 0.01275 , GBP-USD is 1.559 and avg of EUR-USD for the month of February is 1.2030375 etc. 对于如平均EUR-USD在我的例子为当月January为1.19935 ， JPY-USD是0.01275 ， GBP-USD为1.559和平均EUR-USD的月February是1.2030375等。
I want array of averages of EUR-USD or may be some other currency pair, of each month ie. 我想要每个月的EUR-USD平均数组，也可以是其他一些货币对，即。 it should be like 它应该像
`[1.19935, 1.2030375, ......]`
query-result = [avg. 查询结果= [平均 of EUR-USD for January, 2006 , avg. January, 2006的EUR-USD汇率， of EUR-USD for February, 2006 , ............., avg. February, 2006的EUR-USD汇率，.............，平均 of EUR-USD for January, 2013 , ..... ] and so on up to 8 years. January, 2013的EUR-USD January, 2013 ，.....]等，最长8年。
Please help me in writing this in single query.Thanks 请帮助我在单个查询中编写此代码。谢谢
1 个解决方案
解决方案1
1 已采纳 2014-06-06 07:08:24
Take parts of date you want (in your case year and month) and group result on this base and currency: 取一部分日期（以您的年份和月份为例），并根据此基准和货币对结果进行分组：
SELECT DATE_FORMAT(rate_date,'%M, %Y') AS rate_month,currency_pair,AVG(rate) AS avg_rate
FROM historical_currencies_rate
WHERE currency_pair='EUR-USD'
GROUP BY DATE_FORMAT(rate_date,'%M, %Y'),currency_pair
ORDER BY rate_month
声明:本站的技术帖子网页，遵循CC BY-SA 4.0协议，如果您需要转载，请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.