如何从日期列中剥离时间并使每个日期的用户数唯一

Question

I've got an incident table that contains far too columns within it. I'm wanting to query 3 of the columns, DateTimeResolved, Team and Individual. Firstly I'd like to ditch the time from the DateTimeResolved column to be left with a date. Then I'd like to know how many individuals (unique count) from each team resolved incidents since April 2017.

Can this be done?

I've got the below queries working but they obviously need tweaking as they don't give me the end result I want.

select stat_datetimeresolved, resolvedbyteam, resolvedby 
from [dbo].[Incident]
where Stat_DateTimeResolved is not null
and Stat_DateTimeResolved >= '2017-04-01 00:00:00'
order by Stat_DateTimeResolved asc


select CAST(stat_datetimeresolved as date),
COUNT(resolvedby)
from [dbo].[Incident]
group by CAST(Stat_DateTimeResolved as DATE)
order by CAST(stat_datetimeresolved as DATE) asc

Answer 1

You were close; you can add a DISTINCT keyword to a COUNT to get the number of unique team-members by day.

SELECT CAST(stat_datetimeresolved as date) as DateResolved
, ResolvedByTeam
, COUNT(DISTINCT resolvedby) as ResolvedByCnt
FROM [dbo].[Incident]
 WHERE Stat_DateTimeResolved >= '20170401'
GROUP BY CAST(Stat_DateTimeResolved as DATE), ResolvedByTeam
ORDER BY CAST(stat_datetimeresolved as DATE) asc, ResolvedByTeam

Answer 2

You have multiple incompatible requests in your question here. I think what you are after is actually:

How many members of each team have made a resolution on each day since April 2017?

To do this, you just need to return a unique list of both the Resolution Date, the Team the individual belongs to and who actually made a resolution, then aggregate:

with r as
(
    select distinct cast(stat_datetimeresolved as date) as DateResolved
                   ,ResolvedByTeam
                   ,ResolvedBy
    from [dbo].[Incident]
    where Stat_DateTimeResolved >= '20170401'  -- NULL check is redundant if you are filtering for a value
)
select DateResolved
      ,ResolvedByTeam
      ,count(ResolvedBy) as NumIndividualsMakingResolutions
from r
group by DateResolved
        ,ResolvedByTeam
order by DateResolved
        ,ResolvedByTeam;