从数据库表MYSQL中选择2个随机成员

I have a query below. On executing it, it returns all the results where i can see multiple records for each single memberid.

I want to select the profiles of two members randomly chosen without any performance issue.

SELECT
  a.memberid,
  a.category_id,
  a.content,
  a.count_cid,
  a.importance
FROM tb_profilingdata a,
  tb_member b
WHERE a.memberid = b.memberid
    AND a.category_id IN($catstr)
    AND a.memberid NOT IN('$mid',$seen)
    AND b.gender = 'male'
ORDER BY a.memberid, a.category_id

I tried some queries for choosing one random record

SELECT
  r1.memberid
FROM tb_profilingdata AS r1
  JOIN (SELECT
      (RAND() * (SELECT MAX(DISTINCT(memberid)) FROM tb_profilingdata)) AS memberid) AS r2
WHERE r1.memberid >= r2.memberid
ORDER BY r1.memberid ASC
LIMIT 1

But it chooses in total 1 record out of tb_profilingdata whereas i want records of one randomly chosen member.

I tried the same query with tb_member, but it is possible that a member present in tb_member might not have its entries in tb_profilingdata..

Please suggest me a good way out with least performance issues.

May be that will help you:

SELECT [something] FROM [source] WHERE [conditions] ORDER BY RAND() LIMIT 2

This query is untested unless you provide some sample data

SELECT
  a.memberid,
  a.category_id,
  a.content,
  a.count_cid,
  a.importance
FROM tb_profilingdata a
  left join (select
           memberid
         from tb_member
         group by memberid
         order by rand()) b
    on a.memberid = b.memberid
WHERE a.category_id IN($catstr)
    AND a.memberid NOT IN('$mid',$seen)
    AND b.gender = 'male'
ORDER BY a.memberid, a.category_id