distinct value which has maximum id

Question

I am facing a problem in mysql query,i have 2 table.

1. category_info

    cid cname 1 Latest News 2 Notice Board 3 Headline 

2. news_info

    pid cid title date 1 1 mobile 2013-03-04 2 1 fish 2013-03-04 3 2 Airtel india 2013-03-04 4 2 Marco Simoncelli 2013-03-05 5 3 title1 2013-03-22 6 1 title 2013-03-22 7 3 International Opportunity 2013-03-22 

I want to access title from table news_info distinct value which has maximum pid

I am using following query

SELECT a.*, b.*  FROM category_info AS a RIGHT JOIN news_info AS b ON (a.cid = b.cid)  GROUP BY a.cid

it give me distinct value but not max id. it give min id value.

Answer 1

This will give you the answer to the question that you asked. I'm not sure if it's what you actually want though.

select distinct title
from news_info
where pid = 
(select max(pid) from news_info)

Answer 2

Here is another approach:

select ni.*
from news_info ni
order by pid desc
limit 1

In your example, there are no duplicate pids, so there is only one with the maximum value.

Answer 3

Here is yet another approach:

SELECT *
FROM news_info n
LEFT JOIN category_info c ON a.cid = b.cid
--
-- the maximum pid := there should not exist a higher pid value (for the same cid)
--
WHERE NOT EXISTS (
   SELECT * FROM news_info x
   WHERE x.cid = n.cid
   AND x.pid > n.pid
    );