title: Can MySQL generate random numbers that can be either negative or positive?
body: <p>Is there any way in MySQL to generate a random number that can be either positive <em>or</em> negative?</p>
  
  <p>For example, I want a double between <code>-1.0</code> and <code>1.0</code> rather than a double between <code>0.0</code> and <code>1.0</code> which is what <a href="https://dev.mysql.com/doc/refman/5.0/en/mathematical-functions.html#function_rand" rel="nofollow">RAND()</a> returns.</p>