查询mysql中的days函数

Question

我的表名为sales。它包含如下列的列。

fld_id  int(11),
fld_date    date,
fld_state   varchar(45),
fld_dtcode  varchar(45),
fld_companyname varchar(150),
fld_unitrate    int(11),
fld_count   int(11),
fld_amount  int(11),

我想了解过去30天销售的平均值。
请帮助我找到销售的平均值

Answer 1

试

select avg(fld_count*fld_amount) as average
from sales
where fld_date > now() - interval 30 day

SQLFiddle example

Answer 2

您只需使用AVG()

SELECT AVG(fld_amount * fld_count) AvgSales30
FROM sales
WHERE fld_date > Date_Add(curdate(), interval -30 day)