code: public int update(String sql, Object... paras) {
  		Connection conn = null;
  		try {
  			conn = config.getConnection();
  			return update(config, conn, sql, paras);
  		} catch (Exception e) {
  			throw new ActiveRecordException(e);
  		} finally {
  			config.close(conn);
  		}
  	}
docs: Execute update, insert or delete sql statement.
  @param sql an SQL statement that may contain one or more '?' IN parameter placeholders
  @param paras the parameters of sql
  @return either the row count for <code>INSERT</code>, <code>UPDATE</code>,
  or <code>DELETE</code> statements, or 0 for SQL statements
  that return nothing