Question

I have a table of reports that has these relevant fields:

user_id (int 11)
submitted_date (datetime)
approved_flag (shortint 1)

There are multiple rows per user_id, some with approved_flag = 0 and some with approved_flag = 1 and each with a unique submitted_date.

I need to get a count of the approved and unapproved reports. But I only want to count the most recent submitted report per user (most recent submitted_date), regardless of approved_flag.

So, if there was 4 records like this:

    user_id, submitted_date, approved_flag
    1, 2009-04-01 01:00, 1
    1, 2009-04-01 02:00, 0
    1, 2009-04-01 03:00, 1 (using this record)
    2, 2009-04-02 01:00, 1 (using this record)

the count would be 2 approved and no unapproved, and if we had

    user_id, submitted_date, approved_flag
    1, 2009-04-01 01:00, 1
    1, 2009-04-01 02:00, 0
    1, 2009-04-01 03:00, 0 (using this record)
    2, 2009-04-02 01:00, 0
    2, 2009-04-02 02:00, 1 (using this record)

the count would be 1 approved (user id 2) and 1 unapproved (user id 1).

To summarize one more time because it is not easy to describe: I want the total number of unique users in the table (regardless of # rows per user) and I want it broken down in to ‘approved’ and ‘not approved’ based on the approved_flag of the most recent report per user.

Any help would be greatly appreciated, thanks!

Answer 1

SELECT approved_flag, COUNT(*)
FROM 
  Table t
  INNER JOIN (
    SELECT user_id, submitted_date = MAX(submitted_date)
    FROM Table
    GROUP BY user_id
  ) latest ON latest.user_id = t.user_id
              AND latest.submitted_date = t.submitted_date
GROUP BY approved_flag