SQL Query to return most recent row WITH an additional filter

Question

Very much stuck with a certain query I'm trying to run.

Here's the table structure -

+--------+----------+--------+
| caseID | status   | update | 
+--------+----------+--------+
     1       New      3-4-2013
     1       Open     3-5-2013
     2       New      3-5-2013
     3       Closed   3-5-2013

I want my query return the most recent row and then only display rows where status = 'New', ie in the sample data only the row caseID = 2 should be returned.

I have this query

SELECT * FROM (SELECT * FROM table ORDER BY update DESC) AS foo GROUP BY caseID

That query returns the most recent row for each caseID. Now I'm struck with the part of just displaying where status = 'New'.

I tried this and got an #1064 SQL error

`SELECT * FROM (SELECT * FROM table ORDER BY update DESC) AS foo GROUP BY caseID WHERE status = 'New'

I tried this and it returns all rows where status='New' even if they are not the most recent. Which is not what I want.

SELECT * FROM (SELECT * FROM table ORDER BY update DESC) AS foo WHERE status = 'New' GROUP BY caseID

I appreciate the help in advance.

Answer 1

Something like this should work.

select * from data
  join (select caseId, max(`update`) as 
           `update` from data 
           where status = 'New' 
           group by caseId) as filter
     on filter.caseId = data.caseId and filter.`update` = data.`update`
where data.status = 'New'
  group by data.caseId;

Basically, you're joining the table to itself, but the inner join is identifying the most recent record that you're trying to retrieve.

Link to SQL Fiddle

Answer 2

Find the date of the most recent row using group by , then join and filter:

select s.*
from structure s join
     (select caseId, max(update) as maxupdate
      from structure s
      group by caseid
     ) ss
     on s.caseId = ss.caseId and s.update = ss.maxupdate
where s.status = 'New';