`ORDER BY` before `GROUP BY` in a request with INNER JOIN? - mysql

Question

Initially I need to build a query fetching sites from one table ordered by date of newest article (articles placed in the separate table).
I build the following query:
SELECT *
FROM `sites`
INNER JOIN `articles` ON `articles`.`site_id` = `sites`.`id`
ORDER BY `articles`.`date` DESC
GROUP BY `sites`.`id`
I supposed that SELECT and INNER JOIN will fetch all posts and associate a site to each one, than ORDER BY will order the result by descending of post date than GROUP BY will take the very first post for each site and I will get the needed result.
But I'm receiving MySQL error #1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'GROUP BYsites.idLIMIT 0, 30' at line 7
If I place GROUP BY before ORDER BY statement the query is working but it will not give me the newest post for each site. Instead the result will be sorted after the grouping which is not the thing I need (actually I could prefer to order in another way after grouping).
I read several pretty similar questions but they all related to the data stored in a single table making it possible to use MAX and MIN functions.
What should I do to implement what I need?

Answer 1

You can use either a subquery / derived-table / inline-view or a self-exclusion join, e.g.:
SELECT s.*, a1.*
FROM `sites` s
INNER JOIN `articles` a1 ON a1.`site_id` = s.`id`
LEFT OUTER JOIN `articles` a2 ON a2.`site_id` = a1.`site_id`
AND a2.`date` > a1.`date`
WHERE
a2.`site_id` IS NULL
ORDER BY
a1.`date` DESC
The principle is that you select the sites for which there is no article date greater than any other article date.

Answer 2

rewrite the sql to the following syntax -
SELECT `articles`.`article_name`,'sites'.'id','articles'.'site_id'
FROM `sites`,'articles'
WHERE `articles`.`site_id` = `sites`.`id`
ORDER BY 'sites'.'id', `articles`.`date` DESC;
Do something like this in the select statement. Group by function demands that all fields to be grouped. Hence usage of * is not possible.

Answer 3

SELECT * FROM ( SELECT `S.<col1>`, `S.<col2>`, `A.<col1>`,`A.<col2>`,
ROW_NUMBER ()
OVER (PARTITION BY `SITES`.`ID`
ORDER BY `SITES`.`ID` DESC)
RID
FROM `SITES` `S`,`ARTICLES` `A`
WHERE `ARTICLES`.`SITE_ID` = `SITES`.`ID`
)
WHERE RID = 1;
Can you try this?

Answer 4

Finally I came to the solution.
First of all I changed the main query from queering from sites table to queering from articles. Next I added the MAX(date) column to the result.
So the resulting query implementing the thing I need is the following:
SELECT `sites`.`url`,MAX(`articles`.`date`) AS `last_article_date`
FROM `articles`
INNER JOIN `sites` ON `sites`.`id` = `article`.`site_id`
GROUP BY `site_id`
ORDER BY `last_article_date` ASC
Thanks to all of you for giving me hints and right search directions!