title: Add 2 coloumn values together and format output Oracle SQL
body: <p>I am guessing this is a straight forward task but just cannot seem to get this to work. I want to add to column values together and then format the result in Oracle SQL. So i thought i could do something like:</p>
  
  <pre><code>to_char(INVOICE_NET, '9,999,999.99') + to_char(INVOICE_TAX, '9,999,999.99')  AS GROSS_PRICE
  </code></pre>
  
  <p>This fails as i guess these are no longer numbers
  Then i thought this may work:</p>
  
  <pre><code>INVOICE_NET + INVOICE_TAX AS to_char(GROSS_PRICE, '9,999,999.99')
  </code></pre>
  
  <p>This also fails.
  Can anyone put me straight please on this.</p>