Question

I am having to set up a query that retrieves the last comment made on a customer, if no one has commented on them for more than 4 weeks. I can make it work using the query below, but for some reason the comment column won’t display the latest record. Instead it displays the oldest, however the date shows the newest. It may just be because I’m a noob at SQL, but what exactly am I doing wrong here?

SELECT DISTINCT
    customerid, id, customername, user, MAX(date) AS 'maxdate', comment
FROM comments
WHERE customerid IN 
   (SELECT DISTINCT id FROM customers WHERE pastdue='1' AND hubarea='1') 
AND customerid NOT IN 
   (SELECT DISTINCT customerid FROM comments WHERE DATEDIFF(NOW(), date) <= 27)
GROUP BY customerid
ORDER BY maxdate

The first “WHERE” clause is just ensuring that it shows only customers from a specific area, and that they are “past due enabled”. The second makes sure that the customer has not been commented on within the last 27 days. It’s grouped by customerid, because that is the number that is associated with each individual customer. When I get the results, everything is right except for the comment column…any ideas?

Answer 1

I think this might probably do what you are trying to achieve. If you can execute it and maybe report back if it does or not, i can probably tweak it if needed. Logically, it ‘ should’ work – IF i have understood ur problem correctly 🙂

SELECT X.customerid, X.maxdate,  co.id, c.customername, co.user, co.comment
FROM 
    (SELECT customerid, MAX(date) AS 'maxdate'
    FROM comments cm
    INNER JOIN customers cu ON cu.id = cm.customerid
    WHERE cu.pastdue='1' 
    AND cu.hubarea='1' 
    AND DATEDIFF(NOW(), cm.date) <= 27)
    GROUP BY customerid) X
INNER JOIN comments co ON X.customerid = co.customerid and X.maxdate = co.date
INNER JOIN customer c  ON X.customerid = c.id
ORDER BY X.maxdate