title: Oracle query with one extra custom conditional column
body: <p>I have a table with customer data where the table contains customer name, id, age.
  Now I want to write a query where the result contains all customer data(*) and one extra column age group.
  Where the age group is 0-14, 14-25 and 25-50 but this data is nowhere in DB.
  I need to write a condition on select * from the CUSTOMER query.</p>