我有一個包含以下信息聚合函數
date sales
2011-02-13 1
2011-02-13 3
2011-02-13 2
2011-02-14 1
2011-02-14 5
2011-02-14 8
2011-02-15 2
etc ...
我怎麼知道什麼是週期平均量的表? 比如我要得到這樣一個結果: 銷售2,4爲每天期間2011-02-11 - 2011-02-15
我有一個包含以下信息聚合函數
date sales
2011-02-13 1
2011-02-13 3
2011-02-13 2
2011-02-14 1
2011-02-14 5
2011-02-14 8
2011-02-15 2
etc ...
我怎麼知道什麼是週期平均量的表? 比如我要得到這樣一個結果: 銷售2,4爲每天期間2011-02-11 - 2011-02-15
select avg(sales) from table where date <= x and date >= y
您的X和Y的日期如
select avg(sales) from table where date <= '2011-02-15' and date >= '2011-02-11'
如果`date`
是DATE
數據類型:
SELECT SUM(sales)/(1 + DATEDIFF('2011-02-15', '2011-02-11'))
AS AverageSalesPerDay
FROM TableX
WHERE `date` BETWEEN '2011-02-11'
AND '2011-02-15'
如果是DATETIME
或TIMESTAMP
:
SELECT SUM(sales)/(DATEDIFF('2011-02-16', '2011-02-11'))
AS AverageSalesPerDay
FROM TableX
WHERE `date` >= '2011-02-11'
AND `date` < '2011-02-16'
你從哪兒弄來2,4? – SAN