如何使用每周汇总的另一个表中的值创建临时表？

Question

It is a bit difficult to explain but basically I need to create a temporary table (date datetime, #customers int) where #customers is the number of weekly customers pulled from another table. Here's my code.

declare @date datetime
declare @temptable table (date datetime not null,#customers int)

set @date='2018-02-13'

while @date<getdate()
begin
insert into @temptable values 
(@date,
(select count(*) from in_ft_conversion 
where u4='cfa' and sales_date between @date and @date-7))
set @date=@date+7
end

The result is a table with all the correct date entries but 0 in the customer column... Does anybody know what I'm doing wrong? Thanks!

Answer 1

您的日期范围有误，请在BETWEEN中交换日期值，这样您就有了BETWEEN <earlier date> AND <later date>

where u4='cfa' and sales_date between @date-7 and @date))

Answer 2

Why would you use a while loop for this? I think you want something like this:

insert into @temptable (date, num_customers) 
    select dateadd(day, '2018-02-08', weekno * 7)
           count(*)
    from in_ft_conversion cross apply
         (values (datediff(day, '2018-02-08', sales_date) / 7
         ) v(weekno)
    where u4 = 'cfa' and sales_date >= '2018-02-08'
    group by v.weekno;

No loop is necessary.

Your problem is specifically the between comparison:

sales_date between @date and @date-7

The dates are backwards -- the lower bound needs to go first.

But, I also doubt that you want to count weeks with 8 days and have one day overlap on each week. I think the above logic does what you want, but you can adjust the date arithmetic to get the exact dates you want.