title: how to subtract 12 hours 30 minutes from the MySQL from date field
body: <p>I have reduce or subtract 12 hours 30 minutes from the 2011-04-26 05:00:00(in the format YYYY-MM-DD HH:MM:SS) IN MySQL database.</p>
  
  <p>The output should be 2011-04-25 16:30:00.</p>
  
  <p>Are there any date function we can use and subtract?</p>