sql 数据按天按月进行分组统计语句
/*
数据库教程orders表中有一个“total”和一个“createtime”字段，现要当月每一天的total的总,如这个月有31天，就要得到31条total的总和
*/

$sql ="select sum(total),convert(char(10),createtime,120) createtime
from tb
group by convert(char(10),createtime,120)
order by sum(total) desc

";

$sql2 ="select sum(total) 总合, convert(varchar(7),createtime,120) as 月
from orders
group by convert(varchar(7),createtime,120)";

$sql3 = "select sum(total) as 总和 ,convert(char(10),createtime,120) createtime
from tb
where datepart(month,createtime)=datepart(month,getdate())
group by convert(char(10),createtime,120)
";

$sql4 =" select
    convert(datetime, floor(convert(float, createtime))), sum(total)
from
    orders
group by
    floor(convert(float, createtime))
";

/*
上面的四种mssql sql 数据按天按月进行分组统计语句各有各的优点，各位可以试一下。
*/