Question

I have two MySql tables, once for “Locations” and one for “Images”. I need to get a list of the most recent Image taken at a particular set of Locations (which is a comma-delimited list), but I only want to return the record for the most recent Image and I’ve been struggling mightily with getting the right results so far.

So, I have:

Locations:
+---------------------------------------------+
| ID | Name                                   |
|----|----------------------------------------|
|  1 | Indiana                                |
|  2 | Ohio                                   |
|  3 | Illinois                               |
+---------------------------------------------+

Images:
+---------------------------------------------+
| ID | User  | Location  |  Date              |
|----|-------|-----------|--------------------|
|  1 | Ray   | 1         | 2012-06-22         |
|  2 | Robert| 3         | 2011-09-18         |
|  3 | Marie | 1         | 2012-10-01         |
|  4 | Frank | 2         | 2010-12-11         |
|  5 | Debra | 1         | 2008-02-02         |
+---------------------------------------------+

So, right now I have the following:

SELECT Locations.Name, Images.Date, Images.User
FROM Locations INNER JOIN Images ON Locations.ID = Images.Location
WHERE Locations.ID IN ('1','3')
ORDER BY Images.Date DESC

Which returns:

+---------------------------------------------+
| Name        | Date        |  User           |
|-------------|-------------|-----------------|
| Indiana     | 2012-10-01  | Marie           |
| Indiana     | 2012-06-22  | Ray             |
| Illinois    | 2011-09-18  | Robert          |
| Indiana     | 2008-02-02  | Debra           |
+---------------------------------------------+

My question is, how can I get it so that the result returns only the first record with a distinct Location.Name value? So the final, correct result table would look like:

+---------------------------------------------+
| Name        | Date        |  User           |
|-------------|-------------|-----------------|
| Indiana     | 2012-10-01  | Marie           |
| Illinois    | 2011-09-18  | Robert          |
+---------------------------------------------+

Thanks a lot!

Answer 1

SImply uSe group by::

Select tempTable.Name, tempTable.Date, tempTable.User from
(
    SELECT Locations.Name, Images.Date, Images.User, Locations.ID as locationID
    FROM Locations 
    INNER JOIN Images ON Locations.ID = Images.Location
    WHERE Locations.ID IN ('1','3')

    ORDER BY Images.Date DESC

) as tempTable GROUP BY  tempTable.locationID