Question

Using postgres, I would like to retrieve each different packages, but retrieve the most recent package for each group.

For example, I have this table named products:

package_name        price           date
-               |   52500.0 |   20080910
-               |   52900.0 |   20090422
-               |   52900.0 |   20090706
ELITE PACKAGE   |   62200.0 |   20080910
ELITE PACKAGE   |   62500.0 |   20090706
ELITE PACKAGE   |   62500.0 |   20090422
TECH PACKAGE    |   57200.0 |   20080910
TECH PACKAGE    |   58200.0 |   20090706
TECH PACKAGE    |   58200.0 |   20090422

And I would like to get the following result with a SQL query:

-                   |   52900.0 |   20090706
ELITE PACKAGE       |   62500.0 |   20090706
TECH PACKAGE        |   58200.0 |   20090706

I have tried a couple of things that (I think) would have worked in mySQL, but I can’t get it right for postgres.

Is it something possible to do, and how would I do it?

Thanks,

Stephanie

Answer 1

SELECT t.package_name, p.price, t.MaxDate
    FROM (SELECT package_name, MAX(date) AS MaxDate
              FROM products
              GROUP BY package_name) t
        INNER JOIN products p
            ON t.package_name = p.package_name
                and t.MaxDate = p.date