根据某些条件返回具有最大日期的记录

Question

I am trying to write a query from a table that contains 'Activities' for customers. Each activity is stored in a single line so if you call a contact and send an email after, it will be in two separate rows.

ie

Contact Employee  Date              Method  
Jack    John      12/7/15 11:50     Email
Jack    John      12/7/15 11:45     Email
Jill    John      12/4/15 10:19     Call
Rick    Amber     12/8/15 9:40      Call
Dave    Sarah     12/10/15 17:10    Email
Dave    Sarah     12/10/15 17:15    Call
Dave    Sarah     12/10/15 17:20    Email

I would like to return the most recent record for the call and if there isn't a call, then the most recent email.

So the output would return like this:

Contact Employee  Date              Method  
Jack    John      12/7/15 11:50     Email
Jill    John      12/4/15 10:19     Call
Rick    Amber     12/8/15 9:40      Call
Dave    Sarah     12/10/15 17:15    Call

This is the current query I have written:

select FA.ContactID, 
FA.Employee as [ContactedBy], 
FA.CreatedDate as [ContactedDate], 
case when max(FA.CreatedDate) and FA.PrincipalCall = 1 then 'Call'
     when max(FA.CreatedDate) and FA.PrincipalCall = 0 and FA.InboundEmail = 1    then 'Call & Email'
     end as [ContactMethod]

from WorkingData.dbo.FactActivities FA

where FA.CreatedDate >= CAST('12-04-2015' as date)
and (FA.PrincipalCall = 1 or FA.InboundEmail = 1)

Any ideas here?

Answer 1

The row_number window function can help here:

select t.contact, t.employee, t.date, t.method
  from (select *,
               row_number() over (partition by contact, employee
                                  order by 
                                    case when method = 'Call' then 0 else 1 end,
                                    date desc) as rn
          from WorkingData.dbo.FactActivities) t
 where t.rn = 1

Based on your desired results, I am assuming that you are looking for the latest call/email record for every contact/employee combination. If this is not exactly right, you just need to tweak the partition by clause in the query.

Answer 2

thanks to sstan; this is what I finished with:

select t.ContactID, t.Priority, t.ContactedBy, t.ContactedDate, t.ContactMethod

from (select FA.ContactID, 
    case when FA.PriorityLevel is null then 2 else FA.PriorityLevel end as [Priority],
    FA.Employee as [ContactedBy], 
    FA.CreatedDate as [ContactedDate], 
    case when FA.PrincipalCall = 1 then 'Call'
         when FA.InboundEmail = 1 then 'Email'
         when FA.PrincipalCall = 1 and FA.InboundEmail = 1 then 'Call & Email'
         end as [ContactMethod],
    row_number() over (partition by FA.ContactID
                              order by case when FA.PrincipalCall = 1 then 0 else 1 end,
                                FA.CreatedDate desc) as rn
      from WorkingData.dbo.FactActivities FA

      where FA.CreatedDate >= CAST('12-04-2015' as date)
            and (FA.PrincipalCall = 1 or FA.InboundEmail = 1)) t
where t.rn = 1

it doesn't matter who the employee was that made the contact, just that the contact was made with an individual on the list so i removed that from the partition

Answer 3

Consider a UNION query without window functions. Below breaks down by data version type as your posted version does not fully match actual data.

Your simplified posted data version:

-- AGGREGATE FOR CALLS 
SELECT TableName.Contact, TableName.Employee, 
       Max(TableName.Date) AS  MaxOfDate, TableName.Method
FROM TableName
WHERE TableName.Method = 'Call'
GROUP BY TableName.Contact, TableName.Employee, 
         TableName.Method
UNION

-- AGGREGATE FOR EMAILS (WITH NO CALLS)
SELECT TableName.Contact, TableName.Employee, 
       Max(TableName.Date) AS MaxOfDate, TableName.Method     
FROM TableName
WHERE TableName.Method = 'Email'
GROUP BY TableName.Contact, TableName.Employee, 
         TableName.Method
HAVING (SELECT Count(*)
        FROM TableName t2
        WHERE t2.Method = 'Call'
        AND t2.Contact = TableName.Contact 
        AND t2.Employee = TableName.Employee) = 0

---

Actual data version (might need adjusting) :

-- AGGREGATE FOR CALLS 
SELECT FA.ContactID, 
       FA.Employee AS [ContactedBy], 
       Max(FA.CreatedDate) AS [ContactedDate],  
       'Call' AS [ContactMethod]    
FROM WorkingData.dbo.FactActivities FA
WHERE FA.PrincipalCall = 1 AND FA.CreatedDate >= CAST('12-04-2015' as date)
GROUP BY FA.ContactID, 
         FA.Employee
ORDER BY FA.ContactID

UNION

-- AGGREGATE FOR EMAILS (WITH NO CALLS)
SELECT FA.ContactID, 
       FA.Employee AS [ContactedBy], 
       Max(FA.CreatedDate) AS [ContactedDate],  
       'Email' AS [ContactMethod]    
FROM WorkingData.dbo.FactActivities FA
WHERE FA.InboundEmail = 1 AND FA.CreatedDate >= CAST('12-04-2015' as date)   
GROUP BY FA.ContactID, 
         FA.Employee
HAVING 
   (SELECT Count(*)
    FROM WorkingData.dbo.FactActivities FA t2
    WHERE t2.PrincipalCall = 1 AND FA.CreatedDate >= CAST('12-04-2015' as date)
    AND t2.ContactID = FA.ContactID 
    AND t2.Employee = FA.Employee) = 0