Connection conn=pool.getConnection();
try {
  // Begin the transaction
  conn.setAutoCommit(false);  // Not necessary when using AOConnectionPool
  try {
    // Prepared statements are always used to avoid the possibility
    // of embedded SQL from web forms
    PreparedStatement pstmt=conn.prepareStatement(sql);
    try {
      // Set the parameters
      pstmt.set...(...);
      // Execute the query or update
      ResultSet results=pstmt.executeQuery();
      try {
        while(results.next()) {
          // Use results
        }
      } finally {
        results.close();
      }
    } finally {
      pstmt.close();
    }
  } catch(SQLException err) {
    // Log the exact SQL statement that failed.
    System.err.println("SQLException caused by query: "+pstmt.toString());

    // Close the connection, just in case establishing a new connection will
    // clear up the error
    if(!conn.isClosed()) {
      conn.rollback();
      conn.close();
    }

    // Rethrow the exception because this is just connection cleanup, not
    // error handling
    throw err;
  } finally {
    // Commit any successful transactions and end the transaction
    if(!conn.isClosed()) {
      conn.commit();
      conn.setAutoCommit(true);  // Not necessary when using AOConnectionPool
    }
  }
} finally {
  // The connection is always released to the pool
  pool.releaseConnection(conn);
}