title: SQL: Interrupting a query
body: <p>I've worked on a project using a proprietary non-SQL DB where queries could be interrupted and in the codebase there were quite some spots where that functionnality was used and made perfect sense (for example to stop a long running query that gets cancelled by the user, or when a more recent query takes place and renders the previous query obsolete, etc.) and I realized I never really saw that kind of "interrupted queries" previously and thought it could make a good SO question (several questions, but they're all related to exactly the same thing):</p>
  
  <ul>
  <li><p>can SQL queries be interrupted?</p></li>
  <li><p>is this part of the SQL standard?</p></li>
  <li><p>if it's not part of the SQL standard, which SQL DBs allow queries to be interrupted (any example most welcome)?</p></li>
  <li><p>is it common to interrupt a DB query (SQL or not) which you'll know you won't care about the result anymore? (in the codebase I've worked on, it sure helps lighten the server's load) </p></li>
  </ul>