title: subtract in sql using with remaining value
body: <p>I have a question. I got 2 tables, and wanted to create a subtraction between these tables. for example, one table is chocolate and others is total. In chocolate table, there are many values whereas in total, it is only one fixed value. So, I need to minus this total value with these chocolate price which has been paid only. I dont get the idea on how to do this. Need Help! Below is the example;</p>
  
  <p>Chocolate table:</p>
  
  <pre>
  Item    Price    Status
  ----------------------
  Dark     5        1
  White    3        1
  Normal   2        0
  </pre>
  
  <p>Total table:</p>
  
  <pre>
  Item                 Price
  --------------------------
  Chocolate package     $10
  </pre>
  
  <p>so i want the answer should be $2.</p>
  
  <p>Thanks in advance!</p>