title: H2 convert date to milliseconds
body: <p>I am trying to convert date in H2 database into milliseconds.</p>
  
  <p>In order to perform some calculation with milliseconds between two dates, i am trying to convert dates to milliseconds, but i can't find any function that would help me in h2 documentation. </p>
  
  <p>Is there any function that can help me, or should i just create custom H2 function for that?</p>