如何将以下查询更改为按天而不是按月拉？

【问题标题】：How do I change the below query to pull by day and not month?如何将以下查询更改为按天而不是按月拉？
【发布时间】：2020-10-13 23:48:32
【问题描述】：

如何将以下查询更改为按天而不是按月提取？

select CONVERT(CHAR(4), dCompletedDate, 100) + CONVERT(CHAR(4), dCompletedDate, 120) as MonthYear,
count(case when dCompletedDate is not null then 1 else 0 end) as 'Total Completes'
from TProfile a
left join TStudyTable b
on a.lhouseholdid=b.lhouseholdid
where
dcompleteddate >= '1/1/1990' and dcompleteddate < '1/1/2050'
group by CONVERT(CHAR(4), dCompletedDate, 100) + CONVERT(CHAR(4), dCompletedDate, 120)
order by MonthYear

【问题讨论】：

标签： sql sql-server date select count

【解决方案1】：

假设dcompleteddate 是datetime 数据类型，您可以将cast 转换为date：

select 
    cast(dcompleteddate as date) as dcompletedday,
    count(*) as total_completes
from tprofile 
left join tstudytable s on p.lhouseholdid = s.lhouseholdid
where dcompleteddate >= '1990-01-01' and dcompleteddate < '2050-01-01'
group by cast(dcompleteddate as date)
order by dcompletedday

旁注：

我将条件 count() 更改为 count(*)；您正在过滤dcompleteddate，因此可以保证它不是null（即使是，您当前的表达式仍然会计算null 值）
我还更改了 where 子句以使用更标准的文字日期

【讨论】：