Search code examples
mysqlsqlrandomsql-limit

MySQL: Can you specify a random limit?

Is there a way to randomize a limit number in SQL (MySQL)?

What I'd like to be able to do is get a random number of results in a query to use in an insertion subquery without any server-side scripting. The query I'd love to be able to run as a hypothetical illustration is:

SELECT id FROM users ORDER BY RAND() LIMIT RAND() * 1000

Of course that doesn't work, but is there another way to randomize the limit number? There are plenty of examples of randomizing a limited set of results, but I can't find anything on the net about setting a random limit.

Solution

  • How about this:

        SELECT * 
      FROM users
     ORDER BY RAND()
     HAVING RAND() * 1000 < 10

    The clause WHERE RAND() * 1000 < 10 randomly chooses to include each row with a probability of 1%. It's not quite a LIMIT variable clause but will do roughly the same thing.