title: What does the "@" symbol do in SQL?
body: <p>I was browsing through the questions and noticed this:</p>
  
  <pre><code>SELECT prodid, issue
  FROM Sales 
  WHERE custid = @custid 
  AND datesold = SELECT MAX(datesold) 
               FROM Sales s 
               WHERE s.prodid = Sales.prodid
                    AND s.issue = Sales.issue
                    AND s.custid = @custid
  </code></pre>
  
  <p>I was wondering what the "@" does in front of custID?  Is it just a way of referencing the custID from the table being selected?</p>