title: numeric range data type postgresql
body: <p>I have a strange situation in the desing of my DB. I have the case that the type of value of a field can be a normal integer or a number between a range. I explain myself with a example:</p>
  
  <p>the column age can be a number (18) or a range between (18-30). How I can represent this with postgresql?</p>
  
  <p>Thx!</p>