Question

我有一张这样的表：

ID | Type | Value | Timestamp
--------------------------------
 1  | AAA  | 0.5   | day 1 hour 1
 2  | BBB  | 1.5   | day 1 hour 1
 3  | CCC  | 1.8   | day 1 hour 1
.....
11  | AAA  | 0.6   | day 1 hour 2
12  | BBB  | 1.4   | day 1 hour 2
13  | CCC  | 1.5   | day 1 hour 2
.....


ID := Int, PK, AI, and so on
Type := String/Varchar
Value := Double
Timestamp := Unix Timestamp (Int), could be easily changed to date type

我想要的是现在特定时间范围的平均值。例如：

我希望所有AAA和所有BBB平均值为＆＃34;值＆＃34;第1天到第3天。每天有几天每种类型有24个条目。

预期结果将是

Type | Average | Timestamp/Date
-------------------------------
AAA  | 0.5242  | Day 1
AAA  | 0.5442  | Day 2
AAA  | 0.5913  | Day 3
BBB  | 1.4228  | Day 1
BBB  | 1.6924  | Day 2
BBB  | 1.3018  | Day 3

我不确定这是否可以使用mysql。使用PHP可能会更有效率吗？

Answer 1

这会产生您需要的结果吗？

# DROP TABLE IF EXISTS likeThis;

CREATE TABLE likeThis (id INT UNSIGNED, `type` CHAR(255), `value` DECIMAL(2,1), `timestamp` CHAR(255));

INSERT INTO likeThis VALUES
    (1, 'AAA', 0.5, 'day 1 hour 1'),
    (2, 'BBB', 1.5, 'day 1 hour 1'),
    (3, 'CCC', 1.8, 'day 1 hour 1'),
    (11, 'AAA', 0.6, 'day 1 hour 2'),
    (12, 'BBB', 1.4, 'day 1 hour 2'),
    (13, 'CCC', 1.5, 'day 1 hour 2');

SELECT * FROM likeThis;

SELECT type, AVG(`value`) average, LEFT(`timestamp`, INSTR(`timestamp`, 'hour') - 2) timestampDate FROM likeThis GROUP BY `type`, LEFT(`timestamp`, INSTR(`timestamp`, 'hour') - 2);

如果没有，请告诉我，

如果日期存储在不同的字段类型中，如何调整查询，以下是一些示例查询：

# How to aggregate by day on a DATETIME field type timestamp
SELECT type, AVG(`value`) average, DATE_FORMAT(`timestamp`, '%Y%m%d') timestampDate FROM likeThis GROUP BY `type`, DATE_FORMAT(`timestamp`, '%Y%m%d');

# How to aggregate by day on a unix timestamp (stored as INT) field type timestamp
SELECT type, AVG(`value`) average, `timestamp` - `timestamp` % 86400 timestampDate FROM likeThis GROUP BY `type`, `timestamp` - `timestamp` % 86400;

谢谢，

詹姆斯

获取特定时间范围和特定条目类型的值的平均值

1 个答案: