Group By value RAND()

Question

It\'s possible get a random value of the group by?

----------------
 nID |  val
---------------
  A  |   XXX
  A  |   YYY
  B  |   L
  B  |   M
  B  |   N
           


        

Answer 1

Try This

SELECT nID, VAL
FROM (select nID, VAL from T1 order by rand()) as T
group by nID

Answer 2

You can use order by rand() then group by them.

Like

  SELECT nID, VAL FROM (
  SELECT nID, VAL
  FROM T1
  ORDER BY RAND()
  )AS subquery
GROUP BY nID

Answer 3

The following solution is similar in spirit to those from xdazz or jonnyynnoj. But instead of SELECT FROM T1 GROUP BY nID I use a subquery to select all distinct IDs. I believe there is a chance that the performance might differ, so give this one a try as well.

SELECT nID,
  (SELECT VAL
   FROM T1
   WHERE T1.nID = ids.nID
   ORDER BY RAND()
   LIMIT 1
  ) AS VAL
FROM (SELECT DISTINCT nID FROM T1) AS ids

Answer 4

Use a sub-query.

SELECT r.nID,
(SELECT r1.val FROM T1 r1 WHERE r.nID=r1.nID ORDER BY rand() LIMIT 1) AS 'val' FROM T1 r 
GROUP BY r.nID

http://sqlfiddle.com/#!2/357b8/18

Answer 5

SELECT 
  t1.nID, 
  (SELECT 
     t2.var 
   FROM your_table t2 
   WHERE t1.nID = t2.nID ORDER BY rand() LIMIT 1
  ) AS var 
FROM your_table t1 
GROUP BY t1.nID ;