title: Custom order by in sql query
body: <p>I am working a report which require custom order by statement.
  I have 5 categories which I am using for the <code>order by</code> clause. These are my column names 
  student expenses, petty cash expenses, home expenses, daily expenses, Fair expenses.
  I want to order them in report in this manner:</p>
  
  <pre><code>Pettycash
  DailyExpense
  Home Expense
  Fair Expense
  Cash Expense
  </code></pre>
  
  <p>Also if new categories are added that wont effect this order and added in the last. I have tried order by asc and desc also searched some forums but it didnt cleared my concept. Thank you.</p>