SQL SERVER - 当不匹配条件时获取 0 而不是现在的行

Question

首先我要说的是，我不是 SQL 方面的专家，更不用说 SQL SERVER 方面的专家了。

我正在尝试执行以下查询:

基本上它的作用是，对于开始日期和结束日期之间的每一天 获取一些数据并将其插入表变量中。

BEGIN

declare @sdate datetime = dateadd(day, -10, getdate())
declare @edate datetime = getdate()
declare @max int = datediff(day, @sdate, @edate)
declare @sday int = cast(day(@sdate) as int)
declare @i int = 1;

declare @Days2 table (
    [sending_id] varchar(255) not null,
    [day] datetime not null,
    [conversions] int not null
)

while @i <= @max
BEGIN
    declare @ssdate datetime = cast(dateadd(day, (@max - @i) * -1 , @edate) as date)
    declare @eedate datetime = cast(dateadd(day, ((@max - @i) * -1) + 1 , @edate)as date)

    INSERT into @Days2 ([sending_id], [day], [conversions])
    select CS.send_id, @ssdate as [date], ISNULL(count(*), 0) as day_conversion
    from campaigns_history CH
    LEFT OUTER JOIN campaign_sends CS ON CS.campaign_historyID = CH.id
    LEFT OUTER JOIN c C ON C.subid = convert(varchar(255), CS.id)
    LEFT OUTER JOIN conversions_keygen CK ON CK.campaignID = CS.id AND cast(CK.genkey as varchar(255)) = C.clickid
    LEFT OUTER JOIN lead_feed LF ON LF.leadID = CK.leadID
    WHERE
        CH.id = 19
        and isnumeric(C.subid) <> 0
        and C.tstamp > @ssdate
        and C.tstamp < @eedate
    group by CS.send_id

    SET @i = @i+1
END

select * from @Days2

END

我想要实现的是这样的:

sending_id | days        | conversions
---------------------------------------
send-1     |  2017-08-01 | 1
---------------------------------------
send-1     |  2017-08-02 | 0            -- the problem is here
---------------------------------------
send-2     |  2017-08-01 | 1   
---------------------------------------
send-2     |  2017-08-02 | 4        

但我明白了:

sending_id | days        | conversions
---------------------------------------
send-1     |  2017-08-01 | 1
---------------------------------------
send-2     |  2017-08-01 | 1   
---------------------------------------
send-2     |  2017-08-02 | 4  

我知道发生这种情况是因为 -> C.subid = CS.id , C.tstamp >= ...和C.tstamp <= ...意味着没有符合此条件的行。

但我也需要获得 0 行!

请帮助我。

提前致谢，祝编程愉快!

Answer 1

使用左连接，您走在正确的轨道上，但当前的where子句阻止对空白行进行计数。将您的条件移至连接条件，如下所示:

select CS.send_id, @ssdate as [date], count(c.subid) as day_conversion
from campaigns_history CH
LEFT OUTER JOIN campaign_sends CS ON CS.campaign_historyID = CH.id
LEFT OUTER JOIN c C ON C.subid = convert(varchar(255), CS.id)
    and isnumeric(C.subid) <> 0
    and C.tstamp > @ssdate
    and C.tstamp < @eedate
LEFT OUTER JOIN conversions_keygen CK ON CK.campaignID = CS.id 
  AND cast(CK.genkey as varchar(255)) = C.clickid
LEFT OUTER JOIN lead_feed LF ON LF.leadID = CK.leadID
WHERE
    CH.id = 19
group by CS.send_id

同时将 ISNULL(count(*), 0) 替换为 count(c.subid)，这样您就不会得到 1 当 c.subid 为 null 时。