Question

I want to return 3 rows from a table called cars and each car should have a distinct dealer_id , and I want them ordered by ID desc (so that the latest three cars added to the database are the ones returned)

SELECT id,dealer_id,name,model_year 
FROM cars 
GROUP by dealer_id 
ORDER BY id DESC 
LIMIT 3; 

But this query is not returning the latest 3 cars from each distinct dealer_id

Answer 1

If you want the most recent records then you can use something like the following:

SELECT c1.id, 
  c1.dealer_id, 
  c1.name, 
  c1.model_year, 
  c1.date_Added
FROM cars c1
inner join
(
  select dealer_id, max(date_Added) mxdate
  from cars
  group by dealer_id
) c2
  on c1.dealer_id= c2.dealer_id
  and c1.date_Added = c2.mxdate
GROUP BY dealer_id
ORDER BY id desc
LIMIT 3;

See SQL Fiddle with Demo