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Editorial Team
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Asked: 2026-05-14T22:38:14+00:00

I have a large data-set of emails sent and status-codes. ID Recipient Date Status

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I have a large data-set of emails sent and status-codes.

ID Recipient           Date       Status
 1 someone@example.com 01/01/2010      1
 2 someone@example.com 02/01/2010      1
 3 them@example.com    01/01/2010      1
 4 them@example.com    02/01/2010      2
 5 them@example.com    03/01/2010      1
 6 others@example.com  01/01/2010      1
 7 others@example.com  02/01/2010      2

In this example:

  • all emails sent to someone have a status of 1
  • the middle email (by date) sent to them has a status of 2, but the latest is 1
  • the last email sent to others has a status of 2

What I need to retrieve is a count of all emails sent to each person, and what the latest status code was.

The first part is fairly simple:

SELECT Recipient, Count(*) EmailCount
FROM Messages
GROUP BY Recipient
ORDER BY Recipient

Which gives me:

Recipient           EmailCount
someone@example.com 2
them@example.com    3
others@example.com  2

How can I get the most recent status code too?

The end result should be:

Recipient           EmailCount LastStatus
someone@example.com          2          1
them@example.com             3          1
others@example.com           2          2

Thanks.

(Server is Microsoft SQL Server 2008, query is being run through an OleDbConnection in .Net)

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1 Answer

  1. Editorial Team

    This is an example of a ‘max per group’ query. I think it is easiest to understand by splitting it up into two subqueries and then joining the results.

    The first subquery is what you already have.

    The second subquery uses the windowing function ROW_NUMBER to number the emails for each recipient starting with 1 for the most recent, then 2, 3, etc…

    The results from the first query are then joined with the result from the second query that has row number 1, i.e. the most recent. Doing it this way guarantees that you will only get one row for each recipient in the case that there are ties.

    Here is the query:

    SELECT T1.Recipient, T1.EmailCount, T2.Status FROM
(
    SELECT Recipient, COUNT(*) AS EmailCount
    FROM Messages
    GROUP BY Recipient
) T1
JOIN
(
    SELECT
        Recipient,
        Status,
        ROW_NUMBER() OVER (PARTITION BY Recipient ORDER BY Date Desc) AS rn
    FROM Messages
) T2
ON T1.Recipient = T2.Recipient AND T2.rn = 1

    This gives the following results:

    Recipient            EmailCount  Status  
others@example.com   2           2       
someone@example.com  2           1       
them@example.com     3           1
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