检索随机id_post sql

我有下一张桌子

 id_post | post


 24         A
 26         B
 39         C
 57         D

我想检索一个随机的id_post

 SELECT id_post
 FROM  posts
 WHERE rand()

I would like to retrieve a single value 24, 26, 39 or 57 how can I make that work?