title: DATE_ADD functionality in Ingres
body: <p>Many (most? nearly all?) SQL dialects have a way to perform this type of function:
  date_add( MyDate, MyInterval )</p>
  
  <p>I've been through all of the docs, but I cannot find this functionality in Ingres. My immediate goal is to get "MyDate plus 3 months". Does anyone know if there is a simple way to do this that I'm missing?</p>
  
  <p>Note: I realize that it's <strong>possible</strong> to achieve this with existing SQL. But it will involve:</p>
  
  <ul>
  <li>extract the month from my date</li>
  <li>add 3 to this number</li>
  <li>extract the day and year from my date</li>
  <li>use the new day, month, year to create a new date</li>
  <li>But I also need to test to see if I cross a year boundary, so there will be a CASE statement as well</li>
  </ul>
  
  <p>That's an awful lot of SQL for something that's so simple in Oracle, MySQL, PostgreSQL, SQL Server, and all the others I can think of. It makes me hopeful that I'm somehow missing a much simpler alternative.</p>