title: How to return a boolean value from a function in MySQL?
body: <p>I have <code>column a</code> and <code>column b</code> in table <code>emp</code>. I'd like to retrieve values from those columns and find the difference between them with a function. The function would return <em>true</em> for a 0 difference otherwise return <em>false</em>. I don't know how to return a value.</p>
  
  <p>Also, how do I store the retrieved values in a variable? </p>