Question

I’m a little rushed for time so I know I could look for the answer myself but stackoverflow is faster! 🙂

I have a table with data let’s pretend it is product information. the table keeps track of when the product data is updated. If I run a query like

SELECT * FROM productChangeLog where change = 'price changed'

I get results like

id  product  date       change
---------------------------------------------    
236 product1 03/14/2011 'price changed'    
241 product2 03/14/2011 'price changed'    
242 product2 03/14/2011 'description changed'    
512 product1 05/16/2011 'price changed'    
517 product1 05/16/2011 'description changed'

what I want to do is select only the most recent ‘price change’ for each product. what do I need to add to my query so that i would only get row 241 and 512? the higher id is always the more recent change

thanks so much!

Answer 1

SELECT t.max_id, t.product, pcl.date, pcl.change
    FROM (SELECT product, MAX(id) AS max_id
              FROM productChangeLog 
              WHERE change = 'price changed'
              GROUP BY product) t
        INNER JOIN productChangeLog pcl
            ON t.max_id = pcl.id